PG: https://www.babylonjs-playground.com/#AYD85K#43
Why is the island not subtracted correctly?
pinging @bghgary
I don’t know much about CSG, but it looks like the CSG didn’t cut through the top and bottom of the ground? The geometry is there though.
@Deltakosh Who knows CSG better?
Well we implemented the original algo 
Maybe csg is not the right tool here?