From http://www.coeurdalene.org/photogallery.asp:
The Coeur d'Alene Resort Golf Course features the world's only floating golf green. The five million pound man-made island is moved via steel cables attached to the lake bottom to vary the yardage from 75 to more than 175 yards.
World's Only Floating Golf Green — 14th Hole of the Coeur D'Alene Resort Golf Course
By AlbinoFlea @ 2005-09-09 00:45:32
milwhcky
@ 2008-03-04 13:12:04
For what it's worth, there is a floating green in Lake Michigan for 11 days each year at Milwaukee's Summerfest. A small barge is anchored 125 yards offshore as part of a contest awarding a new car or airline tickets to someone getting a hole-in-one.