The unincorporated community of Pirates Cove on the island was the location of one of the stations of the Overseas Railroad.

So called, upper and lower, simply referencing the relative nature of their geographic positions, not as distinct islands.

Plant species native to the island include buttonwood, poisonwood, sea grape and thatch palm.

[2] Of fauna, ibises are found on the island, and dolphins, parrotfish, snapper, barracuda and octopus can be seen in the local waters.

Covering 14 acres (5.7 ha),[3][page needed] Sugarloaf Key has the southernmost KOA campground in North America.