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 in the North and Tumakohua in the South let the ocean renew the water of the lagoon and bring the new nutrients. Thus, it creates an ideal mix for the sea life.