Princess Sirindhorn Wildlife Sanctuary (Thai: เขตรักษาพันธุ์สัตว์ป่าเฉลิมพระเกียรติสมเด็จพระเทพรัตนราชสุดาฯ สยามบรมราชกุมารี), or popularly known as Pa Phru To Daeng (ป่าพรุโต๊ะแดง), or just called Phru To Daeng (พรุโต๊ะแดง) is a largest and most fertile peat swamp forest in Thailand covering an area of 125,625 rais, about 4.9654 km2 (49,654 a) in Mueang Narathiwat, Tak Bai, Su-ngai Kolok, and Su-ngai Padi districts of Narathiwat province in southern Thailand.

"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.

[2] While its officially name honours Princess Maha Chakri Sirindhorn, who first visited here in 1990.

Pa Phru To Daeng contains a variety of flora and fauna with special characteristics.

[5] Pa Phru To Daeng provides habitat to flat-headed cat (Prionailurus planiceps), hairy-nosed otter (Lutra sumatrana), rufous-tailed shama (Trichixos pyrropygus), Malaysian blue flycatcher (Cyornis turcosus), especially black hornbill (Anthracoceros malayanus), one of 13 hornbill species in Thailand.