Tema Reef, also called Tima Reef, is a submerged coral reef in the northern Cook Islands, 23 kilometres (14 miles) southeast of Pukapuka.
No coral or rock shows above water, but the sea breaks heavily over the reef. The reef measures about 550 by 360 metres (1,800 by 1,180 feet), covering a shallow but submerged area of 0.16 square kilometres (0.06 square miles).
Tema Reef Wikipedia
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, 1765. Captain William Williams of the missionary ship John Williams sighted the reef on May 15, 1864. It was again examined by HMS Alert in 1880.