We went to this underground river after a boat journey from the mainland. We reached the island to view where the underground river was. First we were checked by someone sitting on the desk who was not very friendly. It appears to be some government official or something who wasn't interested in any tittle tattle, (he appeard unfriendly so we didn't even tried to speak to him) not realising that the tourist helps with the tourist industry there. There were several cute monkeys so tiny they look liked kittens. They were extremely friendly that people get very close to them which isn't a problem. However, one of the monkeys snatched one of the small bags dangling from a female tourist's neck and ran up to the trees. We found that her passport was in the bag so who knows what happened next. Therefore, be careful getting overfriendly with the monkeys.
The most disappointing thing about the river caves is the atmosphere within the caves. There were so many boats about that the magic of the caves was gone.
There's also no mocking about in the island once the boat trip is finished as we were not allowed to stay in the island too long.