Look at Koh Kong Krao on a chart and it reads less as an island than as a piece of the mainland that the sea got behind. The strait at its northern end, marked on old French charts as the Passe de Lamdam, is under 500 metres across; the southern tip sits less than four kilometres off the coast. Slip through that northern gap and you enter the Bay of Koh Kong, a sheltered basin of some 135 square kilometres pressed between the island and the Cardamom Mountains behind it. The island stretches 19.5 kilometres north to south and averages five to seven across, and its interior is genuinely hilly - the northern high point reaches 360 metres, enough relief to throw off waterfalls where the rock breaks. Those streams run down to freshwater estuaries and lagoons rather than straight into the sea, which is why the beaches here behave so oddly.

The western shore holds six beaches, and most of them have a lagoon of their own sitting just behind the sand, fed by rivers coming down off the peaks. You can swim in salt water and rinse in fresh without walking a hundred metres. From October to late May the Gulf here stays mild, with moderate wind and moderate swell, and the water is clear enough for snorkelling; in the low season the surf runs a long way up the sand, though the rain is not the constant curtain outsiders expect - it comes and goes, and the sun comes with it. Three small fishing settlements share the whole island. Alatang sits on the southeastern corner, Phumi Koh Kong on the west coast, and on the eastern shore is Phumi Thmei, which in Khmer simply means new village.

Koh Kong Krao belongs to the Cardamom rainforest ecoregion, and the monsoon blowing in off the Gulf keeps it in evergreen tropical forest year-round. Macaques move through the canopy, wild boar work the undergrowth, and squirrels are everywhere; overhead there are hornbills, mynahs and small parrots. Atlas moths - Attacus atlas, among the largest moths on Earth by wing area - turn up here too. Along the eastern coast and around the bay the forest gives way to mangrove, tangled and extensive, and that is where the food chain really begins. Offshore, patches of coral and seagrass scatter across the shallows. Whale sharks pass through, harmless filter feeders that alarm swimmers who do not know them. So do sea turtles, dugongs grazing the seagrass, and three cetaceans in trouble almost everywhere else they occur: Irrawaddy dolphins, finless porpoises and Indo-Pacific humpback dolphins.

The emptiness is not an accident, and it is not guaranteed. In June 2020 the Cambodian government stood up a committee under the Minister of Environment specifically to review and oversee construction and development proposals for Koh Kong Krao, because the island falls inside a Special Economic Zone designed to encourage exactly that. The waters around it were expected to be declared a marine national park in 2021; that designation has not visibly followed. What the alternative looks like is a short flight east, on the Botum Sakor peninsula. Botum Sakor National Park is Cambodia's largest at 1,825.85 square kilometres, protected since 1993 - and it lost roughly 229 square kilometres of evergreen forest to illegal logging between 1997 and 2002 alone, before a Chinese developer signed a 99-year concession over 36,000 hectares of it in 2008. Koh Kong Krao is still whole. That is a choice, not a condition.