Which Ocean Is the Warmest?

The Indian Ocean, the third-largest ocean at about 70.56 million square kilometres, is the warmest because the vast majority of its area lies between the Tropic of Cancer and the Antarctic Circle, with much of it in the deep tropics. Its average sea surface temperature is about 22 degrees Celsius overall, with tropical regions consistently above 28 degrees Celsius. The warm waters fuel the Indian Ocean monsoon system, which drives the climate and agriculture of South and Southeast Asia, affecting billions of people. The Indian Ocean is also warming faster than any other ocean basin due to climate change — about 1.2 degrees Celsius since 1900 in the western Indian Ocean. This warming intensifies tropical cyclones, accelerates coral bleaching, and disrupts monsoon patterns. The Indian Ocean Dipole (IOD), an oscillation in sea surface temperatures, can cause droughts in Australia and floods in East Africa.