A warm, shallow sea over the sunken Sunda Shelf, dotted with islands and among the busiest tropical fishing grounds on Earth.
Area
320,000 km²
Ocean basin
Pacific
Location
A shallow tropical sea over a drowned land bridge
Average depth
about 46 m
Maximum depth
about 100 m
Salinity
~32–34 ppt
Temperature
Warm, 27–30°C
Region
Between Java, Borneo & Sulawesi
About the Java Sea
The Java Sea spreads across the shallow Sunda Shelf between Java, Borneo and Sulawesi, nowhere much deeper than 100 metres. In the Ice Ages its bed lay exposed as the plain of Sundaland, linking today’s islands into one landmass. Now it is a warm, island-studded sea and one of the most heavily fished tropical waters in the world.
Did you know?
During the Ice Ages its floor was dry land — a vast plain that joined Java, Sumatra and Borneo into one continent called Sundaland.
Highlights
- Over the drowned plain of Sundaland
- Nowhere much over 100 m deep
- Among the world’s busiest tropical fisheries
Photo gallery
Life in the Java Sea
Creatures, seabirds and marine plants — including some of the rarest and strangest — that live in these waters.
Creatures of the deep
Green sea turtle
The only sea turtle that grazes seagrass as an adult, which tints its fat green.
Clownfish
Lives unharmed among an anemone’s stinging tentacles; every clownfish is born male.
Cuttlefish
A master of disguise with W-shaped pupils that flashes rippling colour across its skin.
Nudibranch (sea slug)
Dazzlingly coloured sea slugs that steal stings — and even sunlight — from the food they eat.
Seabirds
Frigatebird
A pirate of tropical skies; the male balloons a scarlet throat pouch to court mates.
Marine plants & algae
Coralline algae
Stony pink algae that cement coral reefs together and help them grow.
Mangrove
Salt-tolerant coastal trees whose tangled roots shelter young fish and buffer storms.
Surface & deep in the Java Sea
The sea is warm where the Sun reaches it and cold far below. Flip between the sunlit surface and the deep water to feel the difference — these are typical figures for a sea.
Sunlit surface
22°C
typical surface temperature
Seas warm strongly at the surface in summer, but their deeper water stays cold and still — the sunlight simply never reaches it.
Recorded range for the Java Sea: Warm, 27–30°C