The Celebes Sea (or the Sulawesi Sea (Malay: Laut Sulawesi) of the western Pacific Ocean is bordered on the north by the Sulu Archipelago and Sulu Sea and Mindanao Island of the Philippines, on the east by the Sangihe Islands chain, on the south by Sulawesi, and on the west by Kalimantan in Indonesia . The Sea is in the form of a huge basin, and plunges as deep as 6,200 m. It extends 420 miles (675 km) north-south by 520 miles (837 km) east-west and has a total surface area of 110,000 square miles (280,000 square km). The sea opens southwest through the Makassar Strait into the Java Sea.

The Celebes Sea is a piece of an ancient ocean basin that formed 42 million years ago in a setting far from any land mass. By 20 million years ago, crustal movement had pushed the Celebes basin close enough to the Indonesian and Philippine volcanoes to receive volcanic debris. By 10 million years ago the Celebes Sea was inundated with continental debris, including coal, which was shed from a rapidly growing young mountain on Borneo and the basin had docked against Eurasia.

The border between the Celebes and the Sulu Sea is at the Sibutu-Basilan Ridge. Strong ocean currents, deep sea trenches and seamounts, combined with active volcanic islands, result in complex oceanographic features.