Happy Whale Shark Day!

August 30th is Whale Shark Day (Día del Tiburon Ballena) in Mexico, as declared by CONANP, Mexico's National Commission of Natural Protected Areas. During the International Conference on Whale Sharks that was held in July on the Yucatan Peninsula's Holbox Island, it was agreed that this day should be dedicated to whale sharks, their conservation, and education about them.

The whale shark is the world's largest fish, and can reach up to 60 feet (18 m) in length. Its back is gray or dark blue, with light colored markings, and its belly is white. It has a wide, flat head with small eyes on the sides, and a big mouth that extends the entire width of its body (as you can see in this photo). The whale shark moves slowly along the water's surface, filtering large amounts of water and consuming plancton, crustaceans and small fish.

One of the best places to see whale sharks is Isla Holbox, the top destination on our list of Mexico's secret beaches.

Read more about the whale shark from About.com's Guide to Scuba Diving.

_{Carl Roessler / Getty Images}