 The cave can flood up to 5 meters, which is 16 feet during rainy season, and should only be entered between November and April. The water is moving, it's muddy, and there's almost no visibility, said a local guide. And once the cave floods, it's risky, even for experienced divers. Almost everyone in Mayside knows this, so when parents of the wild boars begin to worry about their missing boys, they headed straight to the cave. The boys' plans to visit Tham Long have been discussed in a group chat on a messaging app with other friends.