Princess Sirindhorn Wildlife Sanctuary
Princess Sirindhorn Wildlife Sanctuary, or popularly known as Pa Phru To Daeng, or just called Phru To Daeng is a largest and most fertile peat swamp forest in Thailand covering an area of 125,625 rais, about in Mueang Narathiwat, Tak Bai, Su-ngai Kolok, and Su-ngai Padi districts of Narathiwat province in southern Thailand. It is about 6 km from Su-ngai Kolok railway station.
It is named after Khlong To Daeng, one of three main watercourses flowing through the forest. "To Daeng" is a name of one old magician Muslim woman in folklore, who disappeared in the forest and was said to have finally transformed into a crocodile.
While its officially name honours Princess Maha Chakri Sirindhorn, who first visited here in 1990.
This peat swamp forest is a waterlogged tropical rainforest. Under the dark brown water is soft soil formed by the accumulation of decayed vegetation and animals that slowly decomposed and became peat soil with its layer's thickness of 0.5–5 m. Since the soiled water is slightly acidic, the plants and wildlife species inhabiting the peat swamp forest and adaptable to the type of soil and basin that has expanded over the land for a long time.
Pa Phru To Daeng contains a variety of flora and fauna with special characteristics. The plants growing in this forest have buttresses to support the trunks to stand on spongy ground as well as strong branch roots expanding with stilt roots intertwining to support each other. Interesting plant species in this forest include Egyptian white water-lily and Kong, a herbaceous plant with stolon that float in the water.
Pa Phru To Daeng provides habitat to flat-headed cat, hairy-nosed otter, rufous-tailed shama, Malaysian blue flycatcher, especially black hornbill, one of 13 hornbill species in Thailand.
Fish species include Pseudeutropius indigens, which is the world's newest species of schilbeid catfish, slender walking catfish, and rusty squarehead catfish, a small-sized catfish that looks like a flat-headed catfish, which is popular as ornamental fish.
Natural trails at the Sirindhorn Peat Swamp Forest Nature Research and Study Centre are about long with wooden bridges. Signboards along the trails inform visitors.