Generated a survival single player world with seed -4406247. Looks amazing - well done!!
Turned to right and there's a rectangle missing in the sea, swam over to it and started sinking which didn't happen on the swim out. Something was visible inside the rectangle - maybe the sea floor or some other terrain?
Went back to land and tried to chop a tree, seemed to be taking a long time, turns out it was two trees stuck together. Probably not intended but not really an issue as similar things do happen in nature and they would take longer to cut