The reefs and waters of Kingman Reef support a spectacularly diverse and healthy marine community. Deep diving submersible surveys at the atoll in July 2005 revealed that Kingman is home to stands of some of the oldest deep water corals ever observed, with some gold coral colonies estimated to be 5,000 years old. These reefs support spectacular coral diversity (205 species including 181 stony corals through 2008), an abundance of mushroom corals and anemones on lagoon reefs, and many varieties of table and staghorn corals flourishing on ocean-facing reefs. Kingman Reef also supports among the highest density of giant clams in the Pacific, including the northern range extension of one particularly rare species Tridacna squamosa. Giant clams continue to decline throughout their entire range due to overharvesting and several species are listed by IUCN as depleted or endangered. Hence, Kingman serves as a critically important refuge for the continued existence of these clams. One unidentified brown beaked whale was also observed at Kingman in 2007.
More than 225 fish species have been recorded, including sharks, rays, eels, groupers, jacks, goatfishes, butterflyfishes, damselfishes, mullets, wrasses, parrotfishes, surgeonfishes, and tuna. The Refuge supports a sizable population of bottlenosed dolphins and melon-headed whales, as well as several species of giant clams.
The two small coral rubble ridges that remain emergent at Kingman Reef are periodically washed over, accreting,