The mystery of Wisteria Island

Wisteria Island is a very small island, 645 yards from mainland Key West, and inhabited by 0 humans and thousands of Australian pine trees....and who knows what else?  It's (currently) owned by the federal government.
















Wisteria island is unnatural and mysterious.

Unnatural: because it's not a naturally formed island.  It was man made in the 1890s from the sediment of continually dredging Key West harbor (just like the next door, but developed and inhabited, Tank Island (Sunset Key)).
Mysterious: because who's to know what lurks there....

Wisteria Island, taken from Key West Bight

Close up of Wisteria Island and the boats moored off shore

Tiny Wisteria Island.  What mystery lies under those Australian pines?!