There is a P250 entry permit (together with P40 environmental fee) which must be obtained prior to visiting the underground river makes it harder to visit indiviualy but it is possible even some tour agency can tell you diffeetnt story. But for weekends it can be difficult, especialy in high season. If you want hassle free day take a tour, usually 2000 PHP inclusuve of the permint, transport and lunch. On busy days (weekend) you can wait longer,as we, for the small boat taking you to another boat into the cave. For a long wait you can full fill the waiting by taking another boat tour (45 minutes) to Amazon river, done by locals to see different founa and flora - aroubd 300 PHP. Great to see the sleeping snakes, monitor lizard … We had buffet still lunch before the tour. The tour is amazing, just to see the entrance with a turquoise colur makes it WOW. At the departure you are given audio device/guide. The commentary match the ride, the boatman point out the figures by the ray of light. The bats will accompany you, wear the given helmet to avoid uneatned give from them. The tour takes minutes, it is not cold inside but rather hot and humid. The expeience on the whole was awsome.