A dolphin in captivity, even in a dream, is a tragic sight and one with a wealth of meaning. When you dream of swimming with a dolphin in an aquarium of exhibit it suggests that you see yourself in a form of captivity, restless but restrained, unable to exercise your freedom because of the caprice or selfishness of others. This is this case, especially, if the dolphin you've seen appears anxious or restless. It may also suggest a heavy conscience, one weighed down by the guilt associated with constricting someone in your own life. If in your dream you find yourself trying to free the dolphin then it suggests the latter implication is accurate.
Swimming with a dolphin in the wild, by way of contrast, represents the presence of freedom in your life. It alludes to a general satisfaction with your life and ability to act and are not left wanting for opportunities for fun. This is especially true if the dolphin appears happy and energetic and the experience is joyous. It means you're confident and outgoing and the balanced life you lead leaves you happy and satisfied. Swimming with a pack of dolphins modulates this message, instead suggesting that your life is hectic and, at times, overwhelming. Too much times and energy is dedicated to the pursuit of fun with ever diminishing returns, and possibly consequences for your health. You might consider slowing the pace of your life and finding time for more considered and meaningful activities. If you're attacked by a dolphin in your dream it suggests a thirst for rebellion, a readiness to take on whatever is stopping you from realizing your dreams and savouring your freedom.
If you dream of drowning and being rescued by a dolphin or groups of dolphins it strongly implies that you feel bored with life; your problem isn't a lack of opportunities but an unwillingness to seize those opportunities. You have an aversion towards risks that leaves you missing out on all the fun. You should try to be more outgoing and willing to take chances. If you dream of a person with a dolphin tattoo it is a positive sign, you see them as a close friend and source of enjoyment. If you see an image of a dolphin on or near some object it marks it as something you wish to obtain, a hidden desire that you feel you have the potential to fulfill.