Ocean Life - Coral reefs of Tuvalu: Pacific atolls and platforms

Tuvalu's coral reefs comprise three reef islands and six atolls across seven hundred and ten square kilometres of reef platforms in the Pacific Ocean. The volcanic archipelago features two distinct marine structures. While its atolls form annular reef rims that encircle saltwater lagoons and include natural marine channels, its reef islands are smaller, tabular platforms without saltwater lagoons. Some reef islands feature completely closed rims of dry land, cradling remnants of drying lagoons that have lost direct ocean access.

Source: Wikipedia