The address for the Marathon Key Beach Club resort is:
4560 Overseas Highway, Marathon, Florida 33050
Directions in the Keys are typically given by mile marker. And there are two sides to the Overseas Highway, also known as US-1: Ocean side and Gulf Side. The Marathon Key Beach Club is found between mile marker 49 and 50, on the gulf side of the road. It is directly across from the Home Depot. Highway US-1 runs 100 miles starting in Key West at the infamous Mile Marker “0” and heads north all the way to Key Largo.