The Tu Lan cave trip begins with a countryside hike, then a swim (with headlamps and life jackets) through two spectacular river caves, before emerging in an idyllic valley. Then there's more hiking through dense forest to a 'beach' where rivers merge; this is an ideal campsite. There's more wonderful swimming here in vast caverns. Moderate fitness levels are necessary. Tu Lan is 65km north of Son Trach and can only be visited on a guided tour.
Longer Tu Lan tours are also available. The longer excursions penetrate deeper into the jungle, but as the region is so pristine even day hikes are rewarding. Howard and Deb Limbert, consultants to tour operator Oxalis, discovered these caves in 2010. See the Oxalis website for details and costs of longer tours.