On the second day, venture into the natural beauty and historical sites of Thai Nguyen. Start your day with a visit to Nui Coc Lake, a stunning man-made lake surrounded by lush greenery. Take a boat ride on the lake, explore the islands, and enjoy the tranquility of the surroundings. Next, head to the Museum of the Cultivation of Vietnamese Tea, where you can learn about the history and techniques of tea cultivation in Vietnam. Afterward, visit the Dinh Hoa Revolutionary Base, an important historical site during the Vietnam War. Explore the tunnels, bunkers, and exhibits that depict the struggles and sacrifices of the Vietnamese people. In the evening, relax and unwind at one of the local hot springs, such as Suoi Mo or Suoi Gio, and rejuvenate in the mineral-rich waters.