Last month I ventured into the Abandoned Valley near Phong Nha with a small group of fellow backpackers. We hiked through thick jungle, crossed bamboo bridges over slow-moving streams, and stumbled upon old French colonial ruins hidden under vines. The guide, a local villager, told us stories about wartime use of the valley and pointed out rare orchids along the trail. After a picnic lunch by a hidden waterfall, we returned via a different route that led us through a bat-inhabited cave. This off-the-beaten-path trek was surreal-ensure you have waterproof boots and plenty of water in your pack.