Bottlenose dolphins live in groups called pods, usually of around 10 to 30 dolphins, all related to each other. They use whistles and clicks to talk - and amazingly, each dolphin has its own signature whistle, like a name. Mother dolphins teach their babies the family whistle when they are tiny.
Dolphins are mammals, like us - which means they breathe air and have to come up to the surface every few minutes. Their nostril is on top of their head and is called a blowhole. When you see a dolphin surface, the first thing it does is take a big breath in and out, just like you do after holding your breath underwater.
Around the Azores, dolphins often play in the bow waves of boats - they swim right in front of the boat, leaping in and out of the wave, just for fun. Scientists think this is the dolphin version of children playing on a slide.
Portugal protects the waters around Madeira and the Azores so the dolphins are safe. Boat trips to watch them have to stay a respectful distance away, switch off engines, and let the dolphins come to them if they want to. Many do.