Make a planet in the habital zone that has a earth type atmosphere, it’s 10-20 times bigger than earth as it has a large mountain range going all around the earth as it’s kinda a ring stopping 2 oceans from connecting, in the middle of the mountains there are 4 water falls; one that takes you up and all the way up the mountain and another one that takes you down it to the other ocean, this word has no full on continent like the normal world does but it has small island around the world. (Hope this makes sense, if you want it basically looks like the one piece world)