Are there a lot of stairs/ladders?

Lots of stairs and narrow walk ways. Strollers are not allowed through. Wheel chairs are welcome to board the Berkeley fairy boat on the main and upper deck with use of the lift. Just ask for assistance in the gift shop. If you're older and worried about the submarines; there are easy stairs into the russian sub at both ends. I suggest just visiting the 1st room and the last room ,and not going through the B-39. As for the American sub, the American sub, steep ladder ways in and out, but no bulk heads to crawl through. There 4 tall ships, 2 steam boats, and 2 submarines , you wont get bored here

Yes, on the ships you nees to use them to go to the lower floors, and on the submarine is only one to enter and one to got out, also have on count that is a really small place.