Original music by: Michael Z. Land, Peter McConnell, Clint Bajakian, Robin Goldstein and Joseph White
No I'm not insinuating anything about Captain Kate and her booty. This track happens to play both the themes for Captain Kate's Boat (although I always remember it as Guybrush's-diving-to-the-bottom-of-the-ocean theme) and the Booty Island theme. Captain Kate's Boat theme is the first cab off the rank and @ 00:51 it segues to the part where Guybrush dives down before resuming the theme again @ 1:04. The Booty Island theme starts playing @ 3:19.
Captain Kate's Boat theme is by far my favourite of the two, and I don't think I'm the only one, considering it resurfaces in not only Curse of Monkey Island but Tales of Monkey Island as well.