The park wraps the islands of the Koh Rong archipelago — Koh Rong and Koh Rong Sanloem chief among them, along with Koh Oun, Koh Song Saa, Koh Tatiem, Koh Touch, Koh Manoa Krav and Koh Manoa Knong, plus uninhabited scraps like Koh Koun to the north. It did not appear from nothing. A 405-square-kilometre protected area had been declared in 2016 and managed since 2012 by Fauna and Flora International, the British conservation organisation; the 2018 designation enlarged that footprint by nearly thirty percent and handed responsibility to the Ministry of Environment. Ten and a half kilometres of open sea separate the archipelago from the mainland — far enough to have kept the reefs alive, close enough that everything happening on shore eventually arrives.

The value here is not spectacle so much as inventory. Coral reef, mangrove and — most importantly — seagrass meadow, which is the least photogenic and most consequential habitat in these waters. Seagrass is nursery, pasture and carbon sink at once. Seahorses hold onto it. Sea turtles graze it. Dugongs, the shy and dwindling sirenians of Southeast Asian coastal water, depend on it entirely. The threat is correspondingly unglamorous. Blast fishing and cyanide were once common here and have largely gone, replaced by trawling for shrimp and crab — nets dragged across the bottom that take the catch and the meadow together, and leave scoured sand where a nursery used to be. A reef damaged by dynamite is obvious from the surface. A seagrass bed torn up by a trawl is invisible from six feet above it.

BirdLife International designated the archipelago an Important Bird Area, and the bird responsible weighs about as much as a slice of bread. The Malaysian plover stands fifteen centimetres tall, weighs between thirty-five and forty-two grams, and is near threatened with perhaps ten thousand left in the world. It does not build anything. It scrapes a shallow depression in open sand above the tideline, lays two or three eggs the colour of the beach, and both parents take turns sitting on them for a month, then shepherd the chicks for another month before they can fly. Every element of that strategy assumes an empty beach. A footstep destroys a clutch without the walker ever knowing. An adult flushed off the nest in tropical midday leaves eggs to cook in minutes. On an archipelago now selling itself on its sand, the plover is the species with the least room to negotiate.

Enforcement was the problem in 2018 and it has not stopped being one. Foreign trawlers work these waters, and reporting at the time described fishing access being bought from officials outright; Cambodia then ranked 161st out of 180 countries on Transparency International's corruption index. There is a second complication, larger and entirely legal. Since 2008 the Royal Group, the country's biggest conglomerate, has held a ninety-nine-year lease over Koh Rong, the largest island inside the park's boundary; next door, Koh Rong Sanloem sits under a separate arrangement, its administration passed to a state development corporation that has granted concession rights to another private developer. Roads have since been cut into Koh Rong's interior and resorts continue to go up along the beaches on both islands. The park does not annul either lease. Both hold, simultaneously, over the same reefs and the same nesting sand — which means the future of this place will be decided less by the 2018 declaration than by what gets built, and who is on the water to watch.