Golfo Dulce

Golfo Dulce is a deep-water gulf on Costa Rica's southwestern Pacific coast, enclosed by the Osa Peninsula to the west and the mainland hills to the north and east. It is one of only four tropical fjords in the world — a fjord-like gulf with sufficient depth to stratify into warm surface water and cooler oxygen-poor water below 50 metres. The upper layer supports an unusual concentration of marine life: humpback whales use the calm enclosed water as a nursery from July to October and again from January to March; spinner dolphins and bottle-nosed dolphins work the gulf year-round; whale sharks are reliably present in season. The water surface is typically flat, protected from the Pacific swell by the Osa Peninsula, which gives the gulf the character of a large tropical lake rather than an ocean coast. There is no surf. Mangrove systems line the eastern and northern shores. Local boat operators from Golfito and Puerto Jiménez offer tours; there are no large-scale tourism facilities on the gulf itself.