Biomes don't respect terrain edits, and map editor bug.

[Natural_20]

Using the map editor, lower terrain on an ocean map so that it's below sea level. Load the map, and you'll see that the underwater terrain gets assigned a land biome.

Another, possibly related bug: After loading an edited map, exit and return to the map editor. The edited map will be shown, but attempting to load it won't load the edits.