This was the highlight of the trip for my wife. Despite having to get up at 4:30 am to get the coach, this was truly magical. Once we had travelled to La Carangue in the south-west part of the island, we boarded a speedboat which took us out to sea. The Captain had been doing this every day for around 17 years he told us (at the same time he told us it was his job?! Who could describe sailing everyday to watch dolphins swim and play in their natural habitat as a job!), and knew the normal routes the dolphins took as they passed the island.
Along with other boats, we followed their route until they were visible, and were lucky enough to find a school of approximately 30-40 spinner dolphins, swimming and jumping ahead of us. One we had taken our fill of videos and photos, the boat sped ahead of the dolphins to allow us to get into the water and swim with them as they caught up! It was amazing.
Sadly, I don't have a waterproof camera, but believe me when I say seeing such a large group of dolphins swim around and below you is like nothing else my wife or I had ever experienced, and something we will never forget.