Saba is number 1 in the ferniest places in the World

Saba, a Caribbean island in the Lesser Antilles chain, is a special municipality of the Netherlands. Measuring just 13 square kilometers, it consists essentially of the top of the dormant Mount Scenery volcano (887 m).
Additions to the Fern Flora of Saba, Netherlands Antilles, DAVID B. LELLINGER, American Fern Journal 92(2):93-96 (2002)
There is tourist information here
There is information on accomodation here