Dolphins live in all oceans of the planet and even in some important rivers.
While not all species of dolphins live everywhere, there is a species for each environment. Specifically one of the best-known species, the bottlenose dolphin lives in every ocean of the world except the Arctic and the Antarctic oceans.
The Atlantic spotted dolphin, lives all over the tropical and temperate areas of the Atlantic Ocean avoiding the Artic and Antartic regions.
The Pink Dolphin lives in the Amazon river.