These caves are about 1km northwest of the town, and extend for several kilometers into the earth. There is now a ticket office here. The first cave has lights, but do take a powerful flashlight (torch) anyway in case of emergencies. You'll also need shoes with good traction as inside it's slippery with moisture and bat droppings.
Though the first few hundred meters of the cavern have been equipped with a walkway and lit by diesel-powered electric lights, much of this subterranean system is untouched. If you are not an experienced spelunker, you shouldn't wander too far into the caves; the entire extent has yet to be explored, let alone mapped.
As well as featuring funky stalactites, mostly named for animals, these caves are crammed with bats. Try to time your visit to coincide with sunset (around 6pm), when hundreds of them fly out of the mouth of the cave in formations so dense they obscure the sky. For a dazzling display of navigation skills, sit at the entrance while they exit. Please be aware that bats are extremely light-sensitive, and tempting as it may be, flash photography can disorient and, in some cases, blind them.
The river here gushes from the cave in clean, cool and delicious torrents. You can swim in the river, which has some comfortably hot pockets close to shore.