Hi Aristotelis Zervoudis,

From the sound of it you have considerably more diving experience than I do (I have never even been past 130 feet much less to 78 meters) so my response may not be helpful to you but perhaps it might be helpful to someone else who reads your post.

Penetrating a U-boat is a rather unique experience. I have been inside two of them (a VIIB and a VIIC) a number of times over the years. I encountered a lot of silt in both of them. If you are not very careful you will stir it up. Once stirred up your light won’t penetrate it very well. It just reflects back on you. The techniques and equipment you need to use inside are much the same as in cave diving and there are classes on cave diving available. In my opinion although I have never taken a cave diving class, it would be a good idea to take one or at least try to find an instructor to talk to. You may also be able to find books on the subject. There are also classes on wreck diving but the ones I have heard about don’t focus on going inside. Caves and sunken U-boats have a lot in common however a sunken U-boat is a more extreme example in some ways. It is more confined, its dark, there are obstacles all over the place at odd angles, some of which are sharp, etc. It is also more disorienting. If the sub lies at a list the deck is at an odd angle and the sides along with the things that protrude from them are kind of above you with things that have fallen from them below you.

The sport diving rule of always diving with a buddy is almost impossible to do in a sunken U-boat. Normally he could help you if you get in trouble, he is a source of spare air in the event of equipment malfunction, he can go get help if you need it, and he knows where you are and what you are doing and how much air you have. Unfortunately, he probably won’t be inside with you in a sunken U-boat. With the wreckage lying all around, there just isn’t enough room. SCUBA equipment is normally bulky but this doesn’t cause a problem in normal diving. It will be a problem inside a sunken U-boat. It will want to snag on everything. If it gets cut you might have to ascend without a working BC.

If you have done something like this before you already understand the problem. However, if you haven’t, you might want to consider practicing first in shallow water and inside something that is relatively safe without the sharp obstacles. With a limited air supply at depth and no real backup at hand, any accident in a sunken U-boat can be your last. If you haven’t been inside something underwater in total darkness you will want to find out what it feels like in shallow water first. Remember, the panic syndrome is what kills most divers. Once you start rapid shallow breathing you are in real trouble if you can’t recognize the symptoms and get control back. Simple things like being enclosed in something in the dark and not being sure how to get out induce much more terror underwater than they do on land. Plan your dive carefully. Know your rate of air consumption at the planned depth and understand that you may be working harder or be colder or be more uncomfortable than you normally would be at that depth and therefore you will probably use more air than you normally would. Try to find an experienced partner. Have a plan for all emergencies. Plan to have enough air for emergency decompression stops (for you and your buddy) on the way up even if you intend to make the whole dive a “no decompression dive”. If you have a problem inside you (and your buddy) may be in there longer than you planned. Getting out won’t help much if you don’t have enough air to do the necessary stops on the way up. If you are injured you will need to know how to get help once you reach the surface.

Now as to the ammunition onboard. It will probably be buried in the silt. It will probably not be fused. A lot of the WWII German ammunition will have cases (non-brass) that have already broken down and exposed the powder to seawater. Even live, fused ammunition is not dangerous if you know how to handle it, however it only takes one to kill or injure you and any accident inside a sunken U-boat may be your last. There are several types of munitions I can think of that you could encounter: scuttling charges (perhaps even set to go off), hand grenades (many U-boars carried them), Ammo for the guns (deck guns, AA guns, etc.), torpedoes, and torpedo detonators. There are probably other explosive devices present I am not aware of as well.

Unless you are very familiar with this type of ordnance you will want to avoid it, which of course is the crux of your question. The problem is, you really won’t know where it is. You may or may not know where it is supposed to be. It is not all stored in the same place on every U-boat. Most of this stuff should be secured in its storage locations, however you may encounter it anywhere. The sub is probably not sitting straight up and down. It is probably listing to one side. Cabinet doors are open and their contents spilled out. Depth charges etc. tend to jar things open. Other divers may have gotten into some of it, etc. Anything not in its assigned place will probably be under the silt.

Going inside a sunken U-boat is a risky business, that is a given. Your best chance of not encountering this stuff is to not go in. However, once inside you might want to resist the urge to open cabinets, etc, or dig around in the silt. You will definitely want to make sure you don’t have anything hanging down from you that could get caught on something or that could bump into something. Your console and spare 2nd stage come to mind. Have a good light and a spare as well. Have someone waiting for you outside and have a plan for what he is to do if you don’t come out in time. Having a way to communicate with him while you are inside could also keep you alive. A safety line is one more thing to get caught on something but it can also be used to communicate with the person on the other end. If he does have to come in to get you he may find you easier if you are on the other end of a line. Remember you are going to stir up the silt behind you as you go in. He will have to find you in it and you will have to find your way back out in it. I have found Cylume light sticks helpful. One of them attached to your gear in front & in back might help someone find you in there more quickly if they need to. Drop them on the way in and it may make it easier to find your way back out (pick them up on the way out). Take a separate spare air system with you. Even the small ones might give you enough air to get to where you can reach your buddy or do an emergency ascent.

You have already taken the most important step, you asked the question. Talk to as many experienced people as you can. Going inside will probably be an experience you will never forget. Whether or not it is a good experience may depend on how you plan and rehearse it.

I would be very interested to hear what techniques and equipment you used when you complete the dive. Of course I would also be very interested to hear what you found inside as well.

Have a safe dive,

Ken Dunn