a sea, encircled by islands, of the Pacific Ocean; located in the Malay Archipelago and bordered by the islands of Sumatra, Java, and Kalimantan. The sea is connected to the Indian Ocean by the Sunda Strait. The Java Sea has an area of 552,000 sq km, an average depth of 111 m, and a water volume of 61,000 cu km. The coasts are primarily low and covered by mangrove thickets; some coasts are bounded by coral reefs. The sea’s general depth is 30–80 m. The bottom is composed of sand and sandy silt.

The Java Sea lies in a region of equatorial monsoons. The water has a temperature of 27°–29°C and a salinity of 29.5–33.5 parts per thousand. The surface currents flow east to west in winter and west to east in summer. The sea has regular semidiurnal and diurnal tides with a range of about 1.4 m. Herring, flying fish, and tuna are caught commercially; pearls are gathered. The principal ports on the Java Sea are Jakarta, Semarang, and Banjermasin.