All the dives I've done here have been on the leeward, or west coast side of the island. Dives I've done here include "airplane wreck", the Mahi, Makaha caverns, Land of Oz and some I don't remember the names of. Our dive boat was often surrounded by dolphins when we left the harbour although we didn't see any at the dive sites. The underwater topography is lava rock riddled with tubes and caverns. There isn't much in the way of coral growth in Hawaii, mostly a couple species of small hard coral. Not very colorful. Most of the colour you see is the fish. Small moray eels and octopus are common as are turtles in the shallower areas. The thing that I notice about this part of Oahu is the consistently good visibility. On the deeper dives like the Mahi and the airplane, visibility was around 80-100 feet every time. The shallower dives are more exposed to surge and the visibility drops to a still respectable 50 feet or so.