In SE Asia, I have had great nude experiences in Bali. Unlike the rest of Indonesia (which is Muslim), Bali is Hindu and therefore much more gentle and open to nudity. Especially, in the countryside, it's very common to find villagers bathing together naked in nearby streams, waterfalls or pools. It is gender segregated, so you'll friends or family of the same sex bathing together and socialising. I have often joined them, and people are friendly and strike up conversation. Many of the settings are spectacular. I think the Balinese have an old belief that when you are in water, your nudity is 'invisible' in some way...
Another option across the Andaman Sea is in the Andaman & Nicobar islands close to Thailand, but belonging to India. The Nicobars are off-limits due to a UNESCO protection of ancient aboriginal tribes there, but the Andamans are easily reachable by air (Singapore-Chennai/Calcutta-Port Blair, and then local ferry hopping), or by yacht from Thailand. Several of the island have spectacular and remotes beaches (beach no 7 on Havelock, and any of the beaches on Neil Island). I have gone naked on several of these. These beaches have also been classed by Conde Nast as some of the world's best.