Where the Gulf of Mexico meets the Caribbean Sea, Isla Mujeres is a launching point to swim with the largest fish in the world - the whale shark! During the Summer, hundreds of these sharks gather here to feed on plankton. As the world's largest fish, the whale shark can grow up to 40 feet long and weigh over 20 tons. Although they are massive, these gentle giants pose no threat to humans. The experience of swimming next to these beautiful beasts is absolutely serene.