Whales, dolphins and porpoises are all members of the cetacean family of animals - mammals that live all their lives in the water but who must surface in order to take in air before diving back down to the depths.
They are famous for their intelligence, social interactions and, in the case of whales, their often incredible size. The blue whale (which can only be seen in waters to the far north of Scotland) can reach almost 30 metres long and weigh over 170 tonnes, making it the laregst animal that has ever lived.
Here are the species you are most likely to spot in Scotland.
1. Harbour Dolphin
The most common cetacean in Scotland is the harbour porpoise. These delightful animals are often seen alone, but may form pods if there's plenty of food around in a certain location. They can be seen all around Scotland's coast but are particularly widespread in the west.
2. Orca
Also known as killer whales, despite the name the Orca is actually a large beautiful black and white dolphin. Most commonly seen off the west coast of Scotland and in the Northern Isles, they feed on fish and seals.
3. Humpback Whale
Once extremely rare in Scotland, humpback whales have been seen in greater numbers in recent years as they migrate from feeding to breeding grounds. These giants of the deep can reach up to 17 metres in length during their around 50 years of life. Those lucky enough to see one may see them leap spectacularly out of the water or slap the surface with their giant tail.
4. White-beaked Dolphin
Living in coastal waters all over Northern Europe, the white-beaked dolphins are found throughout northern European and in Scotland are frequently spotted in the Minch, the Outer Hebrides, the Moray Firth and on the Aberdeenshire coast. Aside from the white marking at the end of its nose that gives it its name, it can be distinguished from other dolphin species by its short rounded beak and tall dorsal fin.