Cuxhaven, July 2018

I ended up at the bottom of a lake in an unexpected manner.

Figure anchored at lake bottom

Although not quite like that.

Claudia, my sister, and Roberto, her husband, were spending the summer in Cuxhaven, located on the shore of the North Sea.

The idea came up that I would visit for a weekend.

And then my sister mentioned something along the lines: "You can also dive in a small submarine around here somewhere - that seems like something you'd like to do."

I have been in a submarine once before. That was in Eilat, Israel, way back in 2001, before they sold their proper submarine and replaced it by a submarine-ish looking glass bottom boat.

But that was a long time ago and I had never been in a small 'observation' submarine.

So I sent a couple of mails, found out that they stopped operating on weekends and decided to extend the weekend in Cuxhaven a bit to be able to include a submarine diving trip.

On Friday morning I drove to Kreidesee Hemmoor.

The lake is a bit of an oddity.

It didn't start out as a lake, but as a limestone quarry.

There was a cement factory nearby that used the limestone and they kept digging deeper and deeper to extract the limestone.

Most of the quarry (and soon a lot of the production facilities as well) was below the groundwater level, so water had to be pumped away to keep the quarry dry while operations continued.

At some point the factory closed and the pumps were switched off.

And after half a decade, the quarry became a deep lake.

Which turned out quite nicely for divers.

There are very few deep lakes in northern Germany - many lakes are more like the Dümmersee, which has a maximum depth of 1.5 meters or the Steinhuder Meer with a maximum depth of 2.9 meters (and an average depth of 1.35 meters).

Those are nice for birdwatchers, but a bit too shallow for divers.

The Kreidesee, however, not only has a depth of about 60 meters, it has, as it was a quarry, some steep rock walls, going almost straight down, so there's not only depth, but the deep bits are easily accessible for divers.

And as it is mainly groundwater, the lake doesn't have any currents, which not only makes it easier for beginning divers, but it also means that there's less motion in the water that brings in or swirls up sediments and muddies the water.

As a result, the place became a convenient place for beginning divers to learn.

A diving base was built and became popular. There's now also a camping site specifically for divers. And then it was not only beginners, but support for training professional divers was added as well (as 60 meters is already a depth where recreational divers shouldn't operate - even the 'Advanced Open Water Diver' certification only allows for dives down to 30 meters). So there are now even Nitrox and Trimix filling stations available.

With all these facilities available, the lake attracts around 30000 divers a year.

And at some point the diving station decided that it would be nice to offer submarine tours as well.

So they got this:

Eurosub Kreidesee Eurosub Kreidesee

It's a small submarine for (realistically) a pilot and a passenger.

Officially it can take two passengers, but then it gets pretty cosy in there. (Two people do fit in side-by-side - the critical resource is actually the legroom. There's not much space towards the front of the submarine and most of the time I had my legs sideways. Which only works if there is nobody there.)

Inside Eurosub Kreidesee

Outside it has the size of a small car, but as there are the buoyancy tanks on the side, the inside is a bit smaller. It can go down to 250 meters, but that is not relevant in a lake that's 60 meters deep. (Although they sometimes use it in the North Sea or the Mediterranean Sea, where it becomes more relevant.)

Getting started is a bit tricky. It's easier to get into a 1930's bi-plane than into this submarine. There's a fixed series of steps you and the pilot need to take to get to their seats (passenger goes first, as the pilot blocks the exit when he's in).

Then there are little plastic bags with 10 kg of lead in them, which need to be shifted around to trim the submarine.

And finally, there's the emergency manual.

It's a bit like the plastic safety instructions in the seat pockets of airplanes, but with more information.

A lot more.

If the airplane safety instructions would include information how to fly and land the plane - just in case you would need it - then they would be a lot like those in the submarine.

Not only did the laminated sheets (there's a bundle of them) describe how to get back to surface, they also covered how to operate the engines and how to steer the submarine.

Although, realistically, there are only two emergency procedures you need to know. (Well, really realistically, you don't need to know any of them - it's quite unlikely that there's ever an emergency.)

There's one lever that fills the tanks with air.

If you use that, the submarine will rise like an elevator to the surface. That should be all you ever need.

There's also a big wrench that can be used to undo a large screw nut in the floor of the submarine. If you do that, a 280 kg steel plate will drop to the floor of the lake, making the submarine lighter and drift to the surface. (But that means that later someone needs to figure out how to find and bring a quarter ton of metal back to the surface. And re-attach it to the submarine.)

More important for practical operation was the proper use of the towel.

Sometimes there's condensation on the plexiglass dome. As the plexiglass is easily scratched, it is important that there's no dirt on the towel used to clean it.

So the towel is never put down anywhere. So when entering the submarine, the towel is carefully passed from hand to hand and then hung on a hook next to the window, making sure it never touches a horizontal surface. (And windows are never wiped, only carefully dabbed dry.)

In any case, after safety instructions and towel handling instructions, it was time to go.

We started right outside the 'submarine garage'.

Submarine garage

I didn't read much about the lake before I went there.

I knew that there was an airplane somewhere in the lake, but had assumed that it was shot down in a war or something like this.

But it turned out that they had put a lot of 'decoration' into the lake.

Partly to give the divers something to look at (it's not like the lake has colourful fish or coral reefs as attractions), partly to provide divers with photo opportunities and partly to provide some underwater landmarks (lakemarks?) so divers don't get disoriented.

One of the things in the lake is an old sailboat.

Sunken sailboat Sunken sailboat

It didn't sink accidentally, but was specifically brought to the lake to sink.

Which turned out harder than expected.

They put in holes in the hull, let in run full of water and watched it swim.

It turned out that the previous owner had filled part of the hull with construction foam, so even full of water it remained afloat.

Ultimately, they had to fill it with stones to get it to the bottom of the lake.

A bit further on was one of the old (presumably scratched by a dirty towel) plexiglass domes from the submarine that divers could use as a small air bubble.

Plexiglass dome

There aren't many fishes in the lake, but there were some trouts around.


So far, we had been going mostly along the road.

This used to be the road, now submerged, where the trucks were taking out the limestone to the factory.

Some of the stuff along the road wasn't put in specifically for divers, but just there, such as an old funnel for sand or the red train warning light.

Sand funnel Railroad stop sign

While there had never been a railroad going into the quarry, the stopping light used to have a real purpose.

There was a station where trucks unloaded the rocks that came directly from the quarry, where the rocks were then crushed, ground and turned into powder, before being driven to the factory.

But there could always be only one truck unloading the rocks, so they needed a signal for other trucks to stop for the duration.

Since they did take the cement away from the factory by train, they had a lot of railroad gear and equipment at the factory. So they used one of the signal lights from there to signal to the trucks.

Way to foreman room

We went past a fenced off entrance (there are a couple of rooms behind that, which were originally used by the foreman of the quarry, but after there was a fatal diving accident in there, access to them was blocked) and had a look at the big funnel that led to the rock crushing and grinding machine.

The stone crushing machine is no longer there (it was sold off and removed when the quarry closed), but it's still obvious where the rocks came down the chute and where they came out of the machine and fell into a truck waiting below.

Rock chute

From there we went further up to the 'bridge' (although it's just an extended ramp) from where the rocks were dropped into the chute.

Underwater bridge

On top of the bridge, there was a truck 'unloading'.

The truck was put on the bridge after the lake was flooded, so it was a tricky operation to get it into the proper position - mostly with air filled lifting bags, rope extensions and careful manoeuvring.

There were also a lot of safety issues to be covered. The doors are shut and blocked and the original windows are covered by plexiglass windows, so nobody can enter the driver's cabin and make it a diver's cabin.

Still, people have tried to smash the plexiglass anyway... Sigh.

Sunken truck unloading Sunken truck unloading Sunken truck unloading Sunken truck unloading

The truck is at about 20 meters depth.

From there we followed the quarry wall downwards.

At some points, the old wooden stairway was still visible.

Underwater stairway

As this took us below the depth permissible for recreational divers, we encountered some markers along the stairs where people had marked their 'personal lowest point' by putting something there.

Bear statue to mark diving limit

The little polar bear was the nicest one - most other markers were beer cans.

Next larger stop was at a police boat (there were some minor things on the way, like a tractor trailer, a camping chair or some barrels of 'radioactive waste', but I'm skipping over these).

Sunken police boat Sunken police boat Sunken police boat

They had removed all the interior before putting it on the lake, so it is a hull with no motor, cabin or windows. It was easier to sink than the sailboat (they just opened some valves at the bottom of the hull), even though they were still surprised how long it stayed afloat.

They were even more surprised when they didn't find it afterwards.

The assumption was that the boat would sink like a stone, but it did, essentially, start to glide underwater (with the cabin roof acting a bit like a wing).

In the end, they found it about a hundred meters away from where they had sunk it.

As it lies at about 40 meters below, that's a glide ratio of 2.5:1. Admittedly not much compared to an aircraft (even a helicopter has a better glide ratio an autorotation), but about as good as a human in a wingsuit.

Speaking of flying things - the next stop was at a Piper Cherokee airplane.

It has a slightly odd story.

It used to belong to Alan Sheppard (yes, the Alan Shepard, fifth man on the moon, portrayed by Scott Glenn in "The Right Stuff" and the guy who played golf there, not someone who happened to have the same name) and was, once it was no longer flightworthy, sold as scrap and sunk into the lake.

Originally, it was there in a 'flying' position.

They had some underwater platform it was tied to and, if I understood that correctly, they had put some air-filled water cooler bottles into the plane to keep it buoyant, so it looked like it was 'flying'.

That worked until a group of divers tried a 'group picture' while sitting on the airplane.

Something went wrong and there was a 'plane crash'.

(It seems like there was a bit of an escalating effect - some of the air-filled water bottles either got out, or leaked air, so the plane was going down, the water pressure increased, so more bottles caved in, making the plane sink even faster, until there was a non-buoyant plane full of crushed water bottles on the bottom of the lake.)

So they decided to get another scrap plane, but it in the old position (presumably with a safer construction) and move Sheppard's plane to another place where only professional divers (and the submarine) could go (at a depth of 55 meters).

That didn't work as well as expected - the propeller was still undamaged after sinking to the bottom, but when a group of professional wreck divers tried to move it to the current position, they let it slip from their equipment and it went nose down into the ground.

Underwater Piper Underwater Piper Underwater Piper Underwater Piper Underwater Piper

Note: The skeleton in the plane is for the spooky atmosphere only. Nobody died in that plane.

Visiting time at the plane was cut short due to navigational error.

The submarine can move quite precisely, especially if there are no currents. In some of the places, especially at the drop chute, we went within centimeters of things to look at.

The propellers can be rotated independently 360° each, giving you fine grained control, but if you try to back up a bit while trying to go up as well, you point them forward and down. And if you're close to the powdery bottom of the lake, you throw up a lot of dirt.

Underwater Piper obscured by dirt cloud Underwater Piper obscured by dirt cloud Underwater Piper obscured by dirt cloud Underwater Piper obscured by dirt cloud

So it was a bit like drawing the curtain over the scene - end of show, time to leave.

It was time to leave in any case - we were already well over the planned length of the sightseeing tour.

(Though this is not a technical constraint - the submarine can operate for about six hours, so we could have stayed a lot longer down there. And, as it's a submarine, we could go straight up at the end. No need for decompression stops.)

The bottom of the lake was surprisingly beach-like.

The reason for this is that the original bottom is about 20 meters lower.

When the lake was filled, some of the sides of the quarry got weakened by soil washout and collapsed into the lake, filling up the bottom of the lake. And as sand takes longer to settle down on the ground than rocks and gravel, what's visible from above is the fine sand layer on top.

Which is also, obviously, the sand that gets easiest blown up by the propeller.

We went back up the quarry wall and followed the sunk road back to the starting point.

When we went out, about two hours earlier, there were very few divers in the water (I did see only two).

By now, around noon, the place had gotten quite busy, especially around the training platforms.

There are some practical parts of diving training that need to be done at specific depths (three and six meters), so they put in some platforms into the water to do the training there.

Novice divers can then concentrate on the actual lessons and don't need to worry about maintaining the proper depth.

And they don't throw up sediments from the ground, so can see the instructor and they don't need to wait every couple of minutes for the dirt to settle down again.

Diving lesson on underwater platform Diving lesson on underwater platform Diving lesson on underwater platform Diving lesson on underwater platform

There's also a little 'Chinese Gate' nearby.

That is mainly for novice divers to work on their buoyancy control.

The idea is to get to the gate and dive through it, without touching either the gate or the ground.

Underwater Chinese Gate

And that was it.

We headed back to the pier next to the submarine garage, fastened the submarine to it and the trip was over.

As a GPS does not work in a submarine, I don't have a nice trail showing where, how far and how fast we went.

But we probably just covered a couple of hundred meters.

Partly because the lake isn't that large. (It's about a kilometer long and 250 meters wide.)

But mostly because most of the attractions are close to the diving base.

If they are too far away, then normal divers use up most of their air diving to the place (professional divers have extra oxygen bottles or use depots).

So the big red buoy is probably roughly where the plane is located and the smaller blue buoy (a bit farther out and to the left) is where the police boat is located, which is as far out into the lake as we went. The bridge with the chute and the truck is quite close to the shore, on the right side, about where the lakes goes around a little corner.

Kreidesee Hemmoor

There's also other stuff farther out along the shore, like a (rubber) white shark, a camper van, a sailing yacht, the other airplane and some cars, but as the main reason for going there was the "submarine experience" and not so much "underwater sightseeing", we didn't go there. (I had already seen more than expected, as I hadn't known that there was so much to see in the lake. I had assumed that it would be mostly slightly muddy water and maybe one airplane, so everything beyond that was already a bonus.

A slight bonus, not related to anything underwater (or, anything on earth, really) was a lunar eclipse on the same evening.

Lunar eclipse ending Lunar eclipse ending

The moon didn't rise in Cuxhaven until the eclipse was almost total and it stayed quite low over the horizon, (5.8° at the eclipse maximum), so I didn't see much of it and only managed to snap a few pictures when walking back to the hotel at night, when the moon was almost half visible again.

Next day we (Claudia, Roberto, Sven (one of their friends) and I) went to an Escape Room in Cuxhaven.

I can't write much about it without spoilers (and cameras were forbidden anyway, so no pictures either), but we did quite well as a team for most of the time.

The first parts went really well, with good coordination and spotting the tasks and solving them quickly, but then we got stuck when we discovered more information than we needed.

There was a point where we had only three attempts to solve the final task and we had (at least) four possible answers (we late uncovered another hint that we had overlooked, but that didn't eliminate any of those options.

So things kind of grinded to a halt while we were trying to decide on the most likely answers and in which order we would try them.

It turned out that the answer was supposed to be simpler than we had assumed (and that was, ultimately, the hint we received by the game supervisor), so with some minor prompting, we manage to escape in time.

After escaping, I went up some trees.

There's a 'climbing park' in Cuxhaven, right next to the beach.

The beach isn't visible on the pictures (the climbing area itself is in a forest), but there's a nice view of the beach and the North Sea once you're up on the course.

For me, the main attraction of the park was the number of ziplines.

All courses there have ziplines at the end (and some also a zipline somewhere in between), but there was also an (almost) zipline-only course.

I started out doing the zipline course, which was fun and then went to one of the others. I was almost done with that, when there was the announcement that a thunderstorm was coming up and everyone should finish the course they were doing, but not start another one.

Then there was a break of about an hour, in which we had to wait out the thunderstorm.

But they have a nice little cafe there, so it wasn't too uncomfortable to wait. (And they were relaxed about their 'no eating or drinking with climbing gear' rule. There was long peg outside the cafe where people were supposed to put their gear while being in the cafe, but as that was outside in the rain, nobody wanted to take off their stuff and let it get soaking wet.

When the rain was over, the course was opened again and I did the other courses.

The first one was a bit interesting, as I was the first one on it after the rain and it was wet, so the obstacles were more slippery than normal.

By the time I got to the next one, that had already been used, so it was much drier.

I didn't quite do all the courses. There was one for small children, which used a completely different safety system. So even if I had wanted to give it a try, for the sake of completeness, I couldn't have. And there was a 'partner parcour' that could only be done with two persons at the same time. But I did all the others (which means all four of them).

As I really like ziplines, I then did the zipline course again.

Zipline Cuxhaven Zipline Cuxhaven Zipline Cuxhaven

It brings you close to ground level, but then you climb up along some hanging 'rubber mats' again (and later up another two ladders) to get you back to some altitude. (The 'rubber mat stairs' are the only 'technical elements' on the zipline course.)

Rubber mat stairs

Most of the ziplines are 'within' the grounds of the climbing park, but two longer ones take you across a public playground back again.

Zipline crossing playground Zipline crossing playground

Unfortunately, I've been overdoing it a bit with the "look, no hands" and posing for photographs and when I was on the zipline bringing me back to the climbing park grounds, I grabbed the line from which the harness was hanging too late and didn't manage to swing around in time so that I would arrive at the other end feet first.

So I hit the padding on the other side with my back and bounced right back onto the zipline before I could grab the holding rope.

Wrong way round

I ended up hanging on the zipline about 20 meters away from the end of the line, with no way to go back or forth (the zipline itself was out of reach, so I couldn't grab it and pull myself forward).

One of the climbing supervisors came over to throw me a rope and pulled me to the next platform.

Throwing rope Pulling to platform Arriving safely

On the next zipline, I made sure to behave properly, hold on to the rope in front of me, arrive at the platform feet first, step properly onto the platform and grasp the safety rope firmly.

Proper arrival at zipline platform Proper arrival at zipline platform

While most other courses there end with a zipline to the ground, the last zipline of the zipline course ends on a platform eight meters up.

But it's not far to the end of the course. Pretty much exactly eight meters. Just a single step.

The last element of the zipline course is a 'freefall machine'.

I had been on one of those while doing a 'mine climbing' tour in a slate mine in Wales the previous year, so I had an idea what to expect.

You clip yourself into a rope and step off the platform.

The idea is that you fall for a bit and the machine then slows you down before you hit the ground.

It's essentially a "leap of faith" (having faith that the machine is properly maintained...)

But there's no real "freefall" - the machine makes you descent at a constant and slow rate until you reach the ground.

So there's still the (minor) psychological factor of stepping off a platform eight meters above the ground, but there's not the effect of 'plummeting to your doom', hoping the machine will slow you in time.

Auto-abseil machine Auto-abseil machine Auto-abseil machine

I originally wanted to end after the zipline course, but then decided to have one more go on one of the other courses.

So once more across logs suspended from ropes...

Logs on ropes

...a horizontal ladder...

Horizontal ladder

...the vertical monkey bars...

Vertical monkey bars Vertical monkey bars

...spider web...

Climbing web

...and also the 'climbing boards', which look like they are hard to do, but they put in the easy climbing holds, so you can grab them easily with your hands (instead of having to hold on with a finger or two) and you can also stand on the lower ones (instead of having to balance on your toes), so they are actually easy.

Hanging climbing boards Hanging climbing boards

This climbing course ended with another small zipline (which I tried to do properly again) and I was back on solid ground, returned the gear and left.

Final zipline

Next day I drove back home.

I did a small detour to visit the highest natural 'summit' in Bremen, but that is covered here.

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