Georgian Bay on Lake Huron could almost be called another Great Lake since it is so large. Pictured is an alvar, a limestone plain where rare plants may be found. I used this photo for the cover of my book, The Dynamic Great Lakes. In the Bruce Peninsula, Canada, I hiked the Bruce trail and saw plants found nowhere else. The Bruce Peninsula is a finger of land that is part of the Niagara escarpment. The Door Peninsula in Lake Michigan is also a part of this escarpment.
I cruised the waters of Georgian Bay in a glass bottom boat and saw shipwrecks beneath the green waters. Many shipwrecks also lie under the waters around the Door Peninsula. Sailors used to call this Death's Door.
There are alvars on Wisconsin's Door Peninsula also.