Puttering up and down Juno Beach, Florida, atop an ATV, scanning the sand for endangered sea turtle tracks, Jessica Pate noticed a giant black shadow moving through the shallow water.

On closer inspection, she was shocked to discover a manta ray. An avid diver and biologist, Pate knew people who had swum with these huge fish in Indonesia or Hawaii—but never in the busy coastal waters of South Florida, which is home to more than six million people.

Intrigued by her encounter in 2010, Pate searched for scientific literature on the South Florida manta ray population, but found just one paper from 1998. So she set out to change that. (Read how manta rays form close friendships.)

For more