The Panama Canal

 

Written on the back, "Gatun Locks Panama Canal" Construction of the canal started in 1904 and was finished ten years later in 1914, so if nothing else, we know this picture was taken after that.  The Gatun Locks are on the Atlantic side of the isthmus, near the city of Colon, and right off of Limon Bay.  This view is looking north towards Gatun Lake.  The men standing on the boat on the left side of the print are wearing hats worn by members of the U.S. Navy, though it's quite possible that sailors of other nations, as well as sailors of the merchant marine, might have also worn them.