That plays a part in why dolphins come to the surface every couple of minutes to get a breath of air. Dolphins can actually stay under water for 15 minutes, yet it is seldom that they do. A dolphin usually returns for a fresh breath about every 2-3 minutes, generally staying close to the surface of the water.
Another interesting fact about dolphins is how they locate food. Dolphins send out a click that is made were their mouths. The click bounces off the objects and back to them, allowing them to determine what the object is. This method is very similar to that of an echo.
As you may have noticed, dolphins swim in skools. The skool is always led by the oldest female dolphin. When they are trying to protect their young or traveling a great distance, dolphin families may join with other families in order to create a large dolphin pack and keep themselves safe from predators.