I don't have sauce however I read the articles and an anon posted a graphic in last bread.
This is a tourist area famous for the caves. You can explore the caves and take tours, etc.
They explored the caves, and then there was an increase in the water level for some reason. Imagine they went in a cave that went up, then down, then up again.
there was some sort of flood, and the flood waters are still in the lowest portion of the cave, which is making it so they cannot leave the cave.