Room of wonders

[spicebug]

Hi. There is room of wonders in outer world and i wonder what is this thing for? There is some resembling places in other locations wich looks like dead end with rainbow (in witch woods and indinera edge). Is there some connections between that room and that places?

And an other question. In the Southern shores ive found a stairs going into sea but noone in party are able to go there. So can someone tell what is this thing too and can i somehow go down into the sea? Perhaps maybe there is a scuba somewhere in the game?