The signs say that people should not enter the cave after 1st July. They entered on 23 June and the cave was relatively dry when they went in. They were caught in an unexpected flash flood.
Local teenagers have been using the cave to hangout in for years, probably decades. Like western kids hang out at the beach, skate rink, mall etc for these kids it is a cave.
Here is a local man talking about that fact.
http://www.abc.net.au/news/2018-07-05/thailands-royal-cave-a-magnet-for-teen-adventurers/9946148
Local teenagers have been using the cave to hangout in for years, probably decades. Like western kids hang out at the beach, skate rink, mall etc for these kids it is a cave.
Here is a local man talking about that fact.
http://www.abc.net.au/news/2018-07-05/thailands-royal-cave-a-magnet-for-teen-adventurers/9946148