Kayangan Lake is a small lake walled in by limestone cliffs on Coron Island, and the water is so clear that you can look straight down the drowned rock face to the blocks lying on the bottom. Swim out and the temperature arrives in bands, cool then warm. The lake is about ten metres deep at most. A dark cave called Awuyuk cuts back into the wall at the far end, and a wooden deck at the edge is the only structure on it. Reaching it means about 150 steps up from the jetty in the cove below, and halfway up comes the view Coron is known by: green water, moored outriggers, limestone spires standing over them. Over the ridge the path drops again to the deck, and the lake is suddenly there, closed in on every side.
The bands you swim through are the lake's odd chemistry. Roughly seventy per cent of it is rain-fed fresh water lying over thirty per cent salt that seeps in through the limestone. Very little lives in that mix, and without plankton to cloud it the water stays glass-clear. In the late 1990s the Philippine government named Kayangan the cleanest and greenest inland body of water in the country three years running. The island and its waters belong to the Tagbanua, who won ancestral domain title in 2002, and this is one of thirteen lakes they hold sacred. Their guardians enforce the rules on the water themselves: life vests at all times since two free-divers drowned here in 2017, swimming inside the marked areas, no sunscreen or lotion in the water, no litter, no drones.