by Long-Vietravel on Flickr.Thien duong cave in Quang Binh, the longest cave in Vietnam.By elenacoleby Long-Vietravel on Flickr.Thien duong cave in Quang Binh, the longest cave in Vietnam.#South East Asia, #asia, #stalagmites, #indochina, #landmark|November 23, 2021