Dolphins are intelligent, playful animals that are often seen leaping from the waves as they swim alongside ships at sea. There is no one explanation why dolphins would want to swim near ships -- dolphins, like humans, have individual motivations and preferences. However, there are a few common reasons dolphins might find a ship's company appealing, depending on the type of ship, its passengers and the dolphin’s mood.
A ship full of humans is often an excellent opportunity for a snack. Whether its tourists out at sea who might throw a fish overboard in the hopes of seeing a dolphin or a fishing vessel with packed nets, a boat can make an attractive target for a pod of hungry dolphins. Dolphins have swum beside ships for hundreds of years, and it's likely they've learned from experience that where there are humans, there is also food.
Dolphins love to have fun. Whether it’s jumping into the air, cruising through the water at high speed or interacting with other sea life, dolphins have shown a streak of fun-loving behavior that indicates many things they do are simply for enjoyment's sake. Dolphins may enjoy using the wake from a boat as a speed boost, and they could also enjoy seeing boats and other vessels where they aren’t normally seen.
Because dolphins are so intelligent, they are more courageous and curious than many other animals. Dolphins will approach unfamiliar objects and creatures to learn about them, unless they have a negative association with the item or creature in question. Dolphins may swim alongside boats simply to sate their curiosity as to what the boat is, who is on it and what it's up to.
Dolphins often ride the wake of a boat in order to move quickly through the water while exerting less effort. Similar to the way a surfer catches a wave, a dolphin can ride a boat wake for a bit of forward momentum that enables it to travel great distances without having to do as much of the work. A large wake gives a dolphin plenty of power to use while it travels from one location to the next.