Most dolphins are marine and live in the ocean or brackish waters along coastlines. There are a few species, however, like the South Asian river dolphin and the Amazon river dolphin, or boto, that live in freshwater streams and rivers.

The vast majority of the world's 40+ dolphin species live in the shallow, coastal waters of tropical and temperate oceans across the globe. These areas, specifically along the continental shelves, provide abundant food sources like fish and squid. The most recognizable species, the Bottlenose Dolphin, is found in nearly every ocean except for the frigid Arctic and Antarctic circles. While we primarily think of them as marine animals, a smaller percentage live in brackish waters where rivers meet the sea, and five specific species are found exclusively in freshwater river systems like the Amazon and the Ganges. As of 2026, scientists have noted that climate change is forcing many dolphin populations to migrate into deeper or cooler waters as their primary prey seeks lower temperatures. Despite their wide distribution, they are highly social animals that stay within pods of five to several hundred, often staying in sheltered bays or estuaries that offer protection from predators.