Lam Nam Nan National Park (Thai: อุทยานแห่งชาติลำน้ำน่าน, RTGS: Utthayan Haeng Chat Lam Nam Nan) is a national park in Thailand's Phrae and Uttaradit provinces. The national park covers an area of 999 square kilometres (386 sq mi) and was established in 1998, it is home to rugged mountains and the reservoir of the Sirikit Dam.