Key Vaca is accessible by water, primarily through Boot Key Harbor, which lies on the south side of the island. Due to the shallow waters of the harbor, deep-draft ships cannot be unloaded there. Between 1906 and 1912, Key Vaca functioned as a temporary deep-water port with the addition of the Knight's Key Trestle to the west of the island. Built in order to provide a supply line for the growing Overseas Railroad, the trestle was dismantled and burnt when the railroad was completed.