There are several impressive waterfalls scattered around Koh Pha Ngan, but the huge Nam Tok Phaeng waterfall, located in the Than Sadet National Park, is the most popular and the easiest to access. Situated a little south-west of the island's centre, to get here, take the Thong Sala / Chalokum Road that runs south to the north of the island. After 5km drive from Thong Sala, look for the sign for elephant trekking on your right, and just past that, you will see the waterfall sign on your left. Take a walk up a very narrow, steep concrete path for 250m to the base of the waterfall. Scooters can drive up the path, but it is quite dangerous; and be careful to give way to motorbikes coming the other way, as they cannot easily stop. The water here dries up during the hot summer months, so it is best to check before you go. Provided you are there at the right time year; the waterfall is very impressive. The water cascades down over a series of rocky tiers to two large pools at the bottom. Here, you can take a swim, and if you're the adventurous type, you can even climb up the waterfall. If you're feeling fit, you can hike another 200m up the path, past the falls, and are rewarded with a spectacular mountain top view. Entrance to the waterfall area is free, and there is a small restaurant at the base of the falls serving food and cold drinks.
Ko Pha Ngan