It really was an entrance. The reason why others weren't able to pass this dungeon was that there was no way others could deal with a river monster. Perhaps it could be that those people hadn't thought about freezing the entire river. Even if they could, the level of their weapons wasn't enough to deal with this big monster.
But Shane wasn't those poor systems. He had already updated his weapons and skills so that he could deal with the unsolvable dungeons. And he was right.
The reason why these dungeons remained intact was that none of the weaker systems passed it, and no higher-level people were interested in entering this place for small treasures.
If it weren't for that herb, Shane knew that he also wouldn't have entered this place. He needed to hide his identity well, and if he wandered around dungeons like this, he knew that he would be caught eventually. So it was still safe for him to do random system jobs despite the difficulty.
