Marovo Lagoon is the largest lagoon on Earth enclosed by a double barrier reef — two parallel walls of coral instead of the usual single one. It wraps roughly 700 square kilometres of clear water off the New Georgia Islands of the Solomons, formed as the volcanoes of Vangunu and Nggatokae subsided over millions of years while coral kept building upward around them. The result is a maze of channels, mangrove islets and coral gardens that geologists have long treated as a textbook case of how barrier reefs grow. Hundreds of small islands lie scattered inside it, many raised on old coral and crowned with rainforest; on some, villages of sago-palm thatch stand on stilts over the water, reachable only by outboard canoe. The lagoon has sat on the UNESCO World Heritage tentative list since 2008 and has been called the 'eighth wonder of the world' for over a century.
Life here moves entirely by water. Canoes link the islands, fishermen work the reef passes at dawn, and snorkellers drift over some of the healthiest reefs in the Solomons, where close to half the seafloor is living coral and bottlenose dolphins, turtles and the odd pod of pilot whales pass through. Marovo's men are among the finest wood carvers in the Pacific, shaping bowls and model canoes from rare black ebony and pale-and-dark kerosene wood. There are no roads, no banks and no large resorts; a scatter of village guesthouses and small eco-lodges takes the few travellers who come, most arriving by light plane to a grass airstrip and then by boat. From a hilltop or a small aircraft the full scale finally registers — green islets running to the horizon across a sheet of impossibly clear turquoise, a seascape that looks like almost nowhere else on the planet.