The depths around the perimeter of the reef are generally less than 37 metres, and in places are less than 11 metres. The least depth is 6.1 metres on its north side. Within the reef, in the lagoon, there are depths of exceeding 183 metres. A gap on the northwest side of the reef gives access to this deep water. Depths of more than 2,700 metres are found within 8 km of the reef.