A crew from a Hawaii- based nonprofit returned to Honolulu on a ship carrying nearly 100,000 pounds of marine debris removed from reefs and beaches of the Papaha­naumokuakea Marine National Monument, including about 86,000 pounds of ghost nets cleared from a single reef.

The Papahanaumokuakea Marine Debris Project in a news release said that its team, on the 185-foot M/V Imua, returned to Hawaii on July 30 with the marine debris it collected at the monument, which consists of a 1,300-mile-long string of uninhabited islands of the Hawaiian island chain.

The team of 16 free divers left Honolulu on July 2 for a 27-day cleanup expedition at the monument. PMDP reportedly surveyed 1,100 acres of reef. The divers cut the nets stuck to coral reefs and hauled them by hand onto 19-foot inflatable boats launched from the primary ship.

Some 86,000 pounds of ghost nets the team retrieved came from Kamokuokamohoali‘i, also known as Maro Reef, which is 800 miles from Honolulu and sits in the heart of PMNM. Ghost nets are tangled masses of lost or discarded fishing nets that often get stuck on shallow coral reefs via ocean currents.

“That’s the equivalent of taking a walk through New York’s Central Park and a few surrounding blocks, and finding enough trash to equal the weight of a commercial commuter airliner,” said PMDP President Kevin O’Brien in a statement. “The fact that we are seeing this kind of accumulation in such a single small area is really indicative of the scale of the global marine debris issue. Kamokuokamohoali‘i is one of the most pristine and isolated places on the planet, and if it’s ending up here in these quantities, it means we’ve got a problem.”

The nets smother and break living coral colonies and can endanger animals that get tangled in them. The project team that retrieved the ghost nets reportedly found a single trawl net at the reef that was found plastered across nearly 200 feet of reef. It had smothered most of the living coral underneath.

Kamokuokamohoali‘i itself is an open-ocean coral reef with no emergent dry land, but the shallow portion of the reef is at a depth of less than 10 feet and accumulates marine debris.

The shallow portion is 8 miles in length and “teeming” with life, the nonprofit said. Endangered Hawaiian monk seals, green sea turtles, rays, sharks and reef fish, many found only in Hawaii, are at the reef.

The nonprofit also said Kamokuokamohoali‘i is one of the most diverse coral reefs in Hawaii, with 37 coral species.

About 11,000 pounds of nets and plastic was removed from the shorelines of Kamole, or Laysan Island, and Kapou, or Lisianski Island. The team removed a total of 97,300 pounds of debris.

“An estimated 115,000 lbs of marine debris accumulates on the reefs of Papa­hanaumokuakea each year, and if PMDP isn’t cleaning it up, no one is,” PMDP Executive Director James Morioka said in a statement. “PMDP’s next clean-up mission is in September, with the goal of removing another 100,000 lbs. It’s our goal at PMDP to continue regular clean-up efforts into the future to maintain coral reef health and protect countless animals from entanglement and potential injury or death.”