Fringing reefs becoming atolls#
As these islands move away from their magma sources they erode and subside. The two large islands, Raiatea and Tahaa, share a single fringing reef. The next island to the northwest, Bora-Bora, consists of a highly eroded volcanic remnant with fringing reef.
The last island, Tupai, signifies the destiny of these islands; the fringing reef has become an atoll with the central island below sea level.