Super cool. I have to admit that I've just become a fan of 'National Historic Landmarks'. This is definitely one of the coolest ones. We paid to see the submarine which was very cool. We went on a Friday afternoon and pretty much had the whole submarine to ourselves. We were just in awe of how the guys slept, ate and communicated on the submarine. It took us probably an hour to completely go through it at our own pace and to listen to the audio along the way. Definitely not a good place for people who cant climb stairs or squeeze into small spaces.