Near the opera house, the world’s largest floating ship museum is made up of 20 historical crafts, including fishing boats, a light vessel and a firefighter, all linked by walkways. Shin down into the 69m-long submarine Nordkaparen for a glimpse into underwater warfare. Inside the labyrinthine 121m-long destroyer Småland , in service from 1952 to 1979, hunched figures listen to crackling radio messages, and the bunks look just-slept-in – you half expect to meet uniformed sailors in the dim, twisting passages…