Mexico



From mid-May to mid-September, the waters around Isla Mujeres play host to hundreds of migrating whale sharks. The fish can be found elsewhere (from Honduras to Australia to Mozambique), but nowhere are they reported in greater concentrations than in Caribbean and Gulf of Mexico waters off the northeast corner of the Yucatán Peninsula. In August, researchers counted 420 whale sharks in one area, says Rafael de la Parra of the Domino Project (named for the sharks' speckled markings), which tags the fish and monitors their movements.