Lignumvitae Key Botanical State Park is a Florida State Park consisting of Lignumvitae Key, Shell Key, surrounding submerged lands, and a parcel at the northern end of Lower Matecumbe Key. The islands are located one mile west of U.S. 1 at mile marker 78.5, and can be reached only by private boat or tour boat. Lignumvitae Key was designated a National Natural Landmark by the National Park Service in 1968, recognizing the tropical hardwood hammock on the island.