Carpe Vita
Most spacious & luxurious liveaboard I've seen. Wonderful crew that is very friendly, helpful, and knowledgeable. The dive guides do an excellent job of pointing out both large & small marine life on every dive. The Sri Lankan chef cooks up a nice mix of Western & Maldivian food. The hot tub on the upper sun deck is a great place to relax with a beer after the dive day is done. Diving is done from a dhoni that is large, spacious, and equipped with personal seats for each diver, a hot shower, and big rinse tanks for camera gear.
Dive conditions: I've done two trips on this boat (August 2012 and August 2013) and had similar conditions both times - warm water (mid-80s), moderate vis (30-60 feet), and medium/strong current on most dives. Reef hooks are definitely recommended, and the boat crew will sell you an excellent one they designed and built if you don't already have one.
Marine life: a good mix of big and small. The first few days of each trip were in northern atolls where the macro life is excellent and just waiting to be photographed. Plenty of reef fish around too. You can't swing a dead cat without hitting a handful of eels on each dive. Mantas, sharks, and whale sharks all made an appearance too, along with schools of jacks, tuna, and grouper. Bring a camera. You won't be disappointed.
Accommodations: I have stayed in both the suite on the top deck and a cabin on the main deck. Both are huge, with one king or two double beds depending on the needs of the people in the room. Plenty of hot water in the en suite shower, and enough electrical outlets for charging batteries, lights, etc.
