Written 2 May, 2009
Owners of private islands can set sea level just about anywhere they want. The default is 20 meters, which is the level of the surrounding void.
The problem with jacking the water level up and down is the remaining sims will be at 20, leaving a vertical gap, like this:
Void Sim Your Sim Adjoining Sim
20 m 30 m 20 m
The owners of the New Trail sim cleverly used landscaping to disguise this. Check the waterfall. Water flows from the 20m surrounding seas to the lower level set for New Trail. Clever!