Fakarava, an atoll of 37 miles (60 km) in length and 15 miles (25 km) in width is the second largest of Polynesia after Rangiroa. It is known worldwide for its extraordinary seabed. This undersea wealthiness is due to the geological features of the atoll. Two gaps (or passes), Garuae at the North and Tumakohua at the South let the ocean renew the water of the lagoon and bring the new nutrients. Thus, it creates an ideal mix for the sealife.