Dolphins live in water but they are not fish. They are mammals. They need air. They can stay under the water for many minutes but then they must go to the surface. Dolphins like warm water the best.
Sometimes they swim close to ships. They jump out of the water again and again. They can swim very fast – up to 55 kilometres an hour.
There are small dolphins and big dolphins: some are two or three metres long. Dolphins are not dangerous. They are very clever animals and they love playing. They have smiling faces.