Movies teach us a lot of incorrect information about submarines. For example, have you ever noticed that in some films submarines lay down on the bottom of the ocean to avoid enemy ships? Can they do that in real life or is it completely impossible? Real submarines are much more fascinating than the ones from the movies.
First of all, there really is no good reason for a submarine to go completely on the bottom of the sea. Submarines are typically operational in several hundred meters of depth, but, as you may know, oceans are much deeper than that. This means that in order to reach the bottom, submarine would have to push its safe limits. And that’s not even the hard part. Getting lodged between rocks is a real danger and, of course, it would make a tremendous sound, which would be easily picked up by the enemy.
However, some submarines can actually do that. Namely, diesel-electric submarines that are smaller and lighter. In fact, some of them train this way. For example, German 206-class submarines routinely lie down on the bottom and later get back up. In fact, crews had a tradition of having a little party after reaching the “rock bottom”. And it is a good opportunity for a party, because risks of damaging the ship when it’s simply not moving are very low. However, the story is completely different with nuclear-powered submarines.
Nuclear submarines are much bigger and heavier. Although they are also quite a bit tougher, they cannot lie down on the bottom of the sea. The risk of getting stuck is too big, but it is also more difficult to perform such manoeuvre safely. Part of the problem are water intake valves that are at the bottom of the hull. Sea water is taken through them in order to provide cooling for the reactor. Some dirt would not cause any damage, but if the ship starts sucking up rocks, it is pretty much asking for trouble. However, there was one nuclear submarine that was actually designed to reach the bottom of the sea.
NR-1 was a submarine developed by General Dynamics. It was not meant to be used by the Navy – it was a rescue and scientific research tool. Up to this day NR-1 is the smallest nuclear submarine in the world and it is actually capable of reaching the seabed. In fact, at the bottom of the hull it has a couple of large wheels that allow the NR-1 to move around when it is laying on the seabed. This way it can be researching the bottom of the ocean without risking damaging the precious hull. This design is not practical for military submarines.
And so yes, it is possible for a submarine to reach the bottom of the sea. However, nuclear submarines would pretty much never do that and diesel-electric submarines are quite rare nowadays. We would like to see that rock bottom party though.