Hi, i know more or less what is world rebasing. i tested it with some landscapes, and it works. but i have a question regarding water planes. how do you set up large waterplanes to not disappear when you go far away from their parent level. i believe you don’t set up several little planes. so how do you do this
One large plane in the persistent level works fine.
Stuff in the persistent level will stay streamed in 
ouch, you mean a good old huge persistent translucent plane. I’ll try it. but i hope it won’t assassinate my ressources
It will. Especially if you are running gerstner and other stuff on it.
a per level custom actor that builds it out using an HISM with LOD system - possibly matching the landscape tile size or half a tile.
Or you can use the community ocean project. They have an infinite plane system on that if i remeber correctly.
it seems that some assets do the job fairy well. you can use several squares, and it works great. so that you can stream. i won’t give any name as i think this is not the place, but i can give you the asset name in PM if needed