Ocean conservationist and photographer Juan Oliphant was diving in water off Oahu's North Shore when he and his group stumbled on a startling discovery.
Twenty-five feet from the shore, they found a dead, young green sea turtle. Fishing line, which had snagged on the reef, was tangled all around the turtle's body, trapping it underwater and keeping it from coming up for air.
"It was the first time I've seen a turtle that was tied to the reef and drowned from it," he told The Huffington Post. "It was cut pretty bad."
Oliphant and his conservation team at One Ocean Diving frequently do underwater cleanup dives around the Hawaiian island of Oahu to clear out trash and debris.
He told HuffPost that during a single cleanup dive earlier this year, they picked up nearly 12 big buckets of monofilament fishing line.
Although the drowned turtle was the first Oliphant has seen killed by line, he says he often sees larger turtles whose fins have been severed because of the heavy fishing line. The coral reefs, he says, also suffer from the pollution.
"The line doesn't break down and it gets tangled around coral heads and kills the coral," he said. "It's actually the most damaging on the coral than anything else. I've seen plenty of coral being suffocated."
Oliphant says a few fishermen have participated in his cleanup dives, giving him some hope that they'll change their practices. By participating, he said, "they can see the damage they're doing" when they leave fishing line behind, "and maybe want to clean up after themselves more."
The green sea turtle is currently listed as a threatened species under the Endangered Species Act. According to the National Oceanic and Atmospheric Administration, ingestion of and entanglement in discarded fishing line is one of the major factors that threatens sea turtles' survival.