Each year, hundreds of thousands of sea turtles make their way to the beaches of Ostional National Wildlife Refuge in Costa Rica in order to lay their eggs.
The refuge, established in 1983, is home to the second-largest gathering of turtles in the world.
Biologist Vanessa Bézy was filming a group of these sea turtles when she realized she was witnessing something special.
“I immediately knew there was something special going on,” Bézy told National Geographic. “To this day I’m still blown away by the video. They look like bumper cars out there.”
There were over five thousand turtles within the area of a football field – covering a total area of over one thousand football fields.
“This is the only time I’ve seen a video capturing this phenomenon in the water,” Roldán Valverde, scientific director of the Florida-based Sea Turtle Conservancy and a biologist at Southeastern Louisiana University, told told National Geographic. “Most of the photography documenting this occurs on the beach.”