Just saw that vid, and it reminded me of something I've really missed while playing Planet Coaster: water. Back in RCT3P we could easily build underwater paths with enclosing tunnels, underwater attractions, if you put your viewpoint under the water it looked like you were under water, etc. I had a little Atlantis section in my favorite park that I've never been able to come close to recreating in Planet Coaster because the bare minimum capabilities were never added.
Innovations for water handling in games have come a long way. Looks to me like there's no good reason not to include significantly better water stuff in Planet Coaster 2.