A warm, shallow tropical gulf ringed by Thailand, Cambodia, Vietnam and Malaysia, scattered with resort islands and coral reefs.
Area
320,000 km²
Ocean basin
Pacific
Location
A shallow, warm tropical gulf of islands and reefs
Average depth
about 45 m
Maximum depth
about 85 m
Salinity
~31–33 ppt
Temperature
Warm, 28–31°C
Region
South-east Asia
About the Gulf of Thailand
The Gulf of Thailand is a shallow, almost-landlocked arm of the South China Sea, bordered by Thailand, Cambodia, Vietnam and the Malay Peninsula. Rarely deeper than 85 m, its warm, calm waters shelter coral reefs and islands like Ko Samui and Ko Tao, and feed fisheries that millions of people depend on.
Did you know?
It is so shallow and enclosed that its warm water is among the gentlest, calmest tropical seas for swimming anywhere.
Highlights
- A shallow, calm tropical gulf
- Dotted with reef-fringed islands
- Vital fisheries for the region
Photo gallery
Life in the Gulf of Thailand
Creatures, seabirds and marine plants — including some of the rarest and strangest — that live in these waters.
Creatures of the deep
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.
Green sea turtle
The only sea turtle that grazes seagrass as an adult, which tints its fat green.
Moray eel
A reef ambush predator with a hidden second set of jaws in its throat to drag prey down.
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.
Turtle grass
A tropical seagrass whose meadows feed turtles, manatees and dugongs.
Surface & deep in the Gulf of Thailand
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 gulf & bay.
Sunlit surface
26°C
typical surface temperature
Shallow and sheltered, gulfs and bays warm up quickly from top to bottom, staying far milder than the deep open ocean nearby.
Recorded range for the Gulf of Thailand: Warm, 28–31°C