Mitiaro, the fourth island in the Cook Islands group, is of volcanic origin. Standing in water 14,750 feet deep (4500 m) it's four miles (6.4 km) across at its widest point. Geography Mitiaro is part of the Nga-Pu-Toru island group formerly, a volcano that became a coral atoll. The coral died forming Makatea. The island is surrounded by the belt of fossilised coral—makatea, between 20 and 40 feet high (6 to 9 m) characteristic of islands in the southern group. The centre is almost flat, q… (More on Mitiaro)