Apo Reef two lagoon systems, the north and south lagoons which are bounded by narrow reef platforms. It is a almost triangular northern and southern atoll-like reefs separated by a deep channel that is open to the west. The channel runs east to west from deep with a fine white sand bottom, numerous mounds and patches of branching corals under the deep blue water. The north lagoon is an enclosed triangular coral reef platform partly exposed during low tide. It is relatively shallow with depths of about . While the south lagoon is an inverted triangular coral platform enclosed on two sides
Tema Reef Tema Reef Tema Reef, also called Tima Reef, is a submerged coral reef in the northern Cook Islands, southeast of Pukapuka. No coral or rock shows above water, but the sea breaks heavily over the reef. The reef measures about , covering a shallow but submerged area of . Legend has it that Tima, an Aitutakian warrior sailed to Nassau, but was chased away by Ngalewu, a chief from Pukapuka. On his return to Aitutaki he passed the reef nearby and named it "Te Toka-O-Tima", the Stone of Tima The reef was sighted by Commodore John Byron on June 21,