Chaloem Rattana Kosin National Park

Limestone caves and forested hills in the Mae Klong watershed make Chaloem Rattanakosin one of Thailand’s smallest but most rewarding national parks. Also known as Tham Than Lot, it protects around 59 square kilometres of forest where a clear stream runs between two famous caves, forming waterfalls and pools that few tourists discover. The park’s out-of-the-way setting in Kanchanaburi province means you’ll often have the trails largely to yourself.

The signature walk links the two caves — Tham Than Lot Noi and the larger Tham Than Lot Yai — following the stream through dense forest past a series of waterfalls. Hornbills call overhead and monitor lizards bask on sun-warmed rocks, while langurs move through the canopy and kingfishers dart along the water. The caves themselves need a torch and sturdy footwear, as the paths can be slippery, and one opens to the sky where the limestone roof has collapsed.

Watch out: The cave floors are wet limestone, not dirt trail — flip-flops and bare feet are a bad idea. Closed shoes with grip, plus a torch each rather than sharing one, make the crossing far safer.

Silence dominates here, broken only by birdsong and the rush of flowing water. The isolation creates an almost primeval atmosphere, and the pools offer refreshing relief from the heat. Early-morning mist rising from the stream adds an atmospheric quality to the forest.

Insider Tip: Visit on a weekday if you can — this park barely registers with the tour-bus circuit that fills Erawan and the Bridge over the River Kwai, so a Tuesday or Wednesday morning here can mean having the stream crossing entirely to yourself.

Visit during the cool season (November to February) when temperatures are comfortable for hiking. The park sits about 97 kilometres north of Kanchanaburi town — hiring a car or motorbike or joining a tour works best, as public transport is limited. Bring plenty of water, insect repellent, and a torch for the caves. Camping is permitted with basic facilities, and the standard national-park fee applies (200 THB for foreign adults, 40 THB for Thais).

For other Kanchanaburi caves and waterfalls, Erawan Waterfall and Khao Laem National Park both make an easy add-on from the Kanchanaburi hub.