A visit to Seaworld or any local aquatic centers that have Dolphins, and be able to see them in real live would be the best idea to celebrate the day.  Unfortunately visiting such a place may not be feasible for many people and for that reason, watching a great Dolphin themed movie might be the best alternative. A good Dolphin movie thats great for the whole family is called "The Dolphin Tale." 
 

There are currently about 300,000 Atlantic White-Sided Dolphins in the world.
 

Dolphins have a very good reputation and relations with humans and are often thought of as a sort of guardian in the ocean. They are highly social animals and are also often regarded as one of worlds smartest animals. Most Dolphin species prefer the warm waters, but there are some that prefer cold climates.  A Dolphins diet is comprised mainly of fish and squid, but some like the killer whale, feed on larger animals like seals. Male dolphins typically mate with multiple females every year, but females only mate every two to three years. Dolphins produce a variety of vocal sounds, usually in the form of clicks and whistles. A common and unique sighting of Dolphins often shows the "Porpoising" which is a term used when they travel, they frequently leap above the water surface,  because jumping saves energy because of the reduced friction while in the air.