Because water temperature varies noticeably across the islands, wetsuit choice is the biggest gear decision divers make before a Galápagos trip. A semi-dry 7mm suit (a quarter-inch, in US sizing) is the standard recommendation for most of the itinerary. In the warmer northern sites, a 5mm suit paired with a rash guard is often enough, while the cooler water around western Isabela usually calls for adding a shorty over a 7mm suit, again with a rash guard underneath. A thin hooded vest, no thicker than 3-4mm and sleeveless so it layers easily, adds meaningful warmth, and the hood can be pulled on or off mid-dive as conditions change. Dive gloves are worth packing too.
Drysuits are generally unnecessary here. They're harder to get in and out of between dives, burn more air, and become genuinely tiring across a multi-dive day — real downsides on a liveaboard doing several dives daily. Anyone bringing one anyway is better off with crushed neoprene than trilaminate.
The vessel itself supplies tanks, weights and weight belts, a surface marker buoy, a Nautilus emergency position transmitter, and a DiveAlert signaling device. Divers are expected to bring their own certification card and log, BCD, regulator and octopus, mask, snorkel, fins and booties, and are strongly encouraged to bring their own dive computer rather than rely on a rental. A camera, dive knife, flashlight, and small repair kit are useful optional extras. Rental equipment is available on board, but the operator's guidance is to bring your own gear whenever possible, both for comfort and for reliability underwater.