Another million-dollar viewpoint that you shouldn't miss when visiting Chiang Muan is the "Old Lignite Coal Mine Viewpoint at Ban Sa." This large, deep reservoir was formed from lignite coal mining and features stunning greenish-blue waters contrasted by the surrounding mountains. It's a perfect spot for taking photographs and enjoying the gentle breeze. Additionally, this site has yielded ancient fossil discoveries during the mining process. Today, Banpu Public Company Limited has enhanced the landscape and set up fossil displays for educational purposes, transforming it into a beautiful tourist attraction.