The warmest ocean in the world is the Indian Ocean. The Indian Ocean, which borders Africa, Asia and Australia on three sides, is located entirely in tropical zones, although it is subject to receiving colder waters from the Southern Ocean.
The typical surface temperature of the warmest portions of the Indian Ocean, in the east-central area is warmer than 82 degrees Fahrenheit. Studies have shown that this temperature has been increasing at a rate in excess of that of other tropical regions since the mid-20th century. This phenomenon is a principal factor in the overall warming of ocean surface temperatures that has been observed since the early 1900s.