Boo Lake is a course in Mario Kart: Super Circuit. It is the second course in the Flower Cup. It is the prequel to Broken Pier. Its background looks like a bunch of dead trees and a mansion, which could be Luigi's Mansion. Ghost Valley 1 and Ghost Valley 2 use it. This tends to be a hard and complicated course with a dangerous shortcut, which is necessary to collect all the coins.
This track is almost identical to Super Mario Kart's Ghost Valley 1, 2, and 3. They both feature Boos floating around the track, but have no affect on the player. They also both have walls that break off if the player hits them. They also have bridges that flicker, disguising the pits.