The central lagoon of Manihiki is enormous — roughly 35 square kilometres of sheltered water ringed by some 40 low coral islets, most of them uninhabited. The water is extraordinarily clear, shifting from turquoise in the shallows to deep blue over the centre. On a calm day the surface is almost mirror-flat.
The lagoon floor is densely populated with pearl farm infrastructure — lines, baskets, and buoys — but also with natural coral formations and a wide variety of fish. Rays and small sharks are commonly seen; turtles nest on some of the outer islets. The combination of pearl farming and healthy marine life makes the lagoon unlike anything else in the Cook Islands.
Access to the lagoon is by boat from Tukao or Tauhunu. There is no hire operation; you travel with whoever can be arranged locally. The journey across to the outer islets takes fifteen to thirty minutes depending on the boat.