Rangko Cave

Rangko Cave is a limestone cave on a small island near Labuan Bajo, with a saltwater pool inside fed by the sea through cracks in the rock. The salt content is high enough that you float without trying. From the outside it's nothing — just a gap in the rock. You go down some steps into the dark and then the water glows blue for no obvious reason.
Once a day, roughly between 2 and 3:30 in the afternoon, a shaft of sunlight hits the opening at exactly the right angle and the whole pool lights up. It lasts about half an hour. Come at any other time and it's still a beautiful cave — just a different experience entirely.
Getting there takes about an hour from Labuan Bajo: a 30-minute drive to Rangko village, a 15-minute boat ride with the local fishermen, then a short walk to the cave entrance. Stalactites cover the ceiling, small fish move around in the water below. The rocks near the edge are slippery — worth knowing before you step.