Giant manta rays are famously gentle and majestic, making them a popular draw for divers and other eco-tourists. They're still giant, though, as one "cheeky" ray recently reminded a marine biologist.

Josh Stewart of Manta Trust was swimming off the coast of Peru in March, part of a project to study how fishing affects local manta populations, when he came across a 15-foot ray. He swam underneath the fish to take a photo ID — every manta has a distinctive pattern of spots on its underbelly — as Shawn Heinrichs of WildAid filmed the interaction, which is captured in the video above.

Suddenly, the manta swooped below Stewart, tucked him into its pectoral fins and carried him along for a brief somersault. The ray then nonchalantly swam away, leaving Stewart awestruck but unharmed.

"I was just swimming down as I usually do to capture a manta ID shot and before I knew it, I was engulfed in the wings of this massive manta as I tumbled through the water," Stewart tells GrindTV. "I suffered no injuries but it was certainly a big surprise."

Manta rays near Peru may have never seen divers or snorkelers before, WildAid points out, since the region has virtually no industry dedicated to diving eco-tourism.

"In all my years of filming and interacting with manta rays, I have never witnessed such an extraordinary interaction between a manta ray and a swimmer," Heinrichs says in a WildAid blog post about the rare encounter. "The power and charisma of this giant manta was truly humbling!"

Giant manta rays off Peru are threatened by targeted fishing as well as accidental bycatch in gill nets, according to WildAid. Stewart and Heinrichs were there to monitor manta behavior and population trends in hopes of assessing the risk faced by rays. On top of studying the animals' status, the project also aims to introduce manta tourism to the region, "which would provide an alternative livelihood to local communities as well as an economic incentive to protecting this vulnerable population."

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Russell McLendon ( @russmclendon ) writes about humans and other wildlife.