Blue Hole (Big Pine Key)
The Blue Hole is an attraction on the island of Big Pine Key in the Florida Keys. It is an abandoned rock quarry that was used for nearby road fills and Henry Flagler's Overseas Railroad. The water it contains is mostly fresh and is used by various wildlife in the area, such as birds, snakes, alligators, key deer and green iguanas. It is part of the National Key Deer Refuge.
Trevellas
The area towards Trevellas Porth is known as "Blue Hills" due to bluish in-ground slate. Trevellas valley has been a site for tin mining for several centuries, and in 1810 the Blue Hills Sett incorporated many of the small mines. Though Blue Hills closed in 1897, tin production has continued in Trevellas to the present and the Blue Hills works can be visited between April and October each year.