Floating architecture firm Waterstudio imagines these off-shore wildlife sanctuaries that would be accessible only to animals and not to humans. The towering parks would provide a bit of green space that lets humans observe—but only from a distance.
Waterstudio's Sea Tree concept would involve using technology similar to off-shore oil storage rigs to provide a haven for flying and swimming animals. The idea is for birds, bats, insects, and fish to have a place undisturbed by humans. The tower would be tethered to the floor so that it can it can move with the wind while remaining moored. However, since they are tethered, it's not as if the Sea Tree could move away from boats or swimmers. I could imagine some humans trying to sneak into the refuge and try to climb up the levels.
You can see more images of the Sea Tree at Waterstudio's website.