. >> narrator: in the shallow, turquoise, clear waters of grand cayman's north sound, dozens of wild southern stingrays glide effortlessly through the sea. >> these southern rays are very, very important to the cayman islands from an ecotourism perspective. >> narrator: tourists from all over the world come to the site to interact with the animals. >> you don't get that kind of experience anywhere else in the world. >> it's the number one water sports attraction on the island. >> it's a hundred foot vis, it's generally calm and the animals are very conditioned. >> narrator: thousands of people each year visit the iconic stingrays of grand cayman, and for more than a decade researchers have been studying the animals. among other things, they want to find out what impact