This one is pretty easy to pin down location-wise, but do you know what year the photo is from? Take a guess (cheaters will be banished!) and we'll update later with the answer and more details. (Here's a larger version!)
UPDATE: This photo was taken in October of 1939. The caption reads: "Pleasure boats docked at the 79th Street boat basin with the high-rise apartments buildings on Riverside Drive in the background."