The latest cleanup expedition to Papahanau- mokuakea Marine National Monument has returned with nearly 53 tons of marine debris — including more than 48 tons of “ghost nets” left behind by fishing operations that had caught on reefs or washed up on shorelines, and more than 4 tons of plastic debris.

The haul by the nonprofit Papahanaumokuakea Marine Debris Project helps illustrate why the monument needs protection: It included a derelict lifeboat from a carrier ship abandoned nearby, beached at a pristine islet with diesel fuel, batteries and engine fluids on board. And two Hawaiian green sea turtles were found entangled in nets.