Silver Springs Florida postcards from the late 1930s.

 I found these three beautiful old Silver Springs postcards recently.  The back of all three are almost totally identical.  They note-

Largest flowing springs in the world, over 750 million gallons daily.  Electric driven glass bottom boats.  Greatest depth 80 feet.  Temperature of water 72 winter and summer.  Shown from sunrise to sunset, in all weather, everyday in the year.

2 are postmarked from Silver Springs, in the late 30s and early 40s.