Coronado Bay, bay of the Pacific Ocean, bounded on the north, east, and southeast by southwestern Costa Rica. The bay, which measures approximately 25 miles (40 km) from northeast to southwest, extends from the town of Quepos southeastward for approximately 60 miles (100 km) to San Pedro (Llorona) Point on the Osa Peninsula. At the mouth of the Grande de Térraba (Diquis) River are numerous islands; farther offshore lies Caño Island. Dominical, on Dominical Point, which protrudes into Coronado Bay, is the principal port.