As one of the steps necessary to support lakes, dikes and lands below the sea level in Outerra, I've made the sea level parametrized. For now it can be set globally to values above or below the mean sea level.
Here are some screens of North America for sea levels of 0, 100, 200, 500 and 1000 meters.
The same for Europe with sea levels of 0, 100, 200, 500 and 1000 meters.
With 500 and 1000m rise the world changes beyond recognition.
While the rise of sea level by 1000m is completely out of proportion and would require some serious biblical sinning or Earth gradually absorbing a body of water with the size of Sedna, it could still serve as a background for a science-fiction based game.
For some opposite change: Great Britain with sea level falling by -20, -50 and -100m respectively:
Lastly, a view from the hills around the Los Angeles sea.