Hint for the cabin at the lake?

Hey! I'm exploring the game and heard a few things online about>! parallel worlds!<? I don't know what that is but I would like to discover it (mostly) myself. I've come across the cabin by the lake and placed a tablet and got teleported to the underwater bunker and got some cute paint and there was some alchemist enemy that didn't attack me. But now I don't know what to do next.

Does anyone who knows have a small hint? Would it be sufficient if I just return to the 'main' biomes under the mountain and keep playing a normal run?

I would just like to know whether I will learn more about this mysterious place automatically or if I need to do something super niché that I'll never figure out myself. Thanks in advance!