West of the southern tip of Elliot Key, on the north side of Caesar Creek.

Named Adams' Key on U.S. Coast & Geodetic Survey of 1862.

According to John C. Gifford, in his "Floridian Keys" written in 1953, Adams Key was the site of the Cocoloba Club, a private resort. An article published in the National Geographic magazine for January 1930 contains an aerial photograph of a small key. The photo clearly shows an Adams Key-shaped island with a large clubhouse and other buildings. The photo caption calls the island Cocolobo Key. Adams Key is within the boundaries of Biscayne National Park. All of the facilities on the key, including the still-standing Cocolobo buildings were totally destroyed in 1992 by Hurricane Andrew, which passed almost directly over Adams Key. According to local legend, Adams Key was the base of operations for the pirate Black Caesar.