Aqua

Aqua is a genuine dive liveaboard, and she's the only one of her kind we list. Twenty-five meters, nine ensuite cabins, 16 divers, eight crew — and a 7-night route that runs north to Darwin and Wolf, which is the whole reason serious divers come to the Galápagos: schooling hammerheads, whale sharks in season, and current-swept walls that have no real equivalent anywhere else.

She carries enriched-air compressors and 12L tanks, an instructor and a divemaster, and a personal marine-rescue GPS beacon and surface marker for every diver — the last of which tells you what kind of water this is. Full personal kit rents for $250 per person if you'd rather not fly with yours.

This one has a hard gate: Advanced Open Water (or equivalent), a minimum of 50 logged dives, and dive accident insurance are all mandatory to board. She also runs a non-diving naturalist route for groups who want the islands without the tanks.