You can only have one island per system. The second player has to inhabit that island and share all resources with the first player. It's a nightmare for my family, where an 18 year old and 12 year old share the same console. The 12 year old freaks out that the 18 year old chopped down a tree and put his tent in the "wrong place." Sure, maybe I'm a bad parent, but why couldn't the game just let me have two islands on a single system, one per switch user? It's a baffling decision that seems to be made just to sell more systems. It's made a fun and peaceful game rage inducing. I don't even want to play it because I don't get to customize *my* island anymore- I have to share it with two kids.