Blue Hole

Blue Hole is a freshwater pond left by a limestone quarry at National Key Deer Refuge on Big Pine Key. It is about three miles north of U.S. 1 on Key Deer Boulevard, with a paved parking area and a short, shaded path to a platform over the water. Keep it on your list if you want a close look at the refuge without a long walk. Give it about 20 minutes, or longer if wildlife is active. There is no restroom, food, or drinking water at the site, so plan for those before turning off U.S. 1.

Alligators are the draw for many visitors, but the water also holds fish and turtles, and the banks attract anhingas, green herons, and other wading birds. Sightings vary, so leave room for a quiet visit. Key deer live throughout the refuge; early morning and the approach to sunset give you a better chance of seeing them. They are the smallest white-tailed deer subspecies and live only in the Lower Florida Keys.

Workers cut the quarry for limestone used in the Overseas Highway. Digging into the island rock opened a freshwater lens held above salt water, leaving a freshwater pool for wildlife on a string of islands surrounded by the sea. Look from the platform across the whole quarry, then notice how quickly the shaded native vegetation closes in around it.

Tarpon are saltwater fish, but storm surges from Hurricanes Wilma in 2005 and Irma in 2017 pushed them into Blue Hole, where some became trapped. Finding one in a freshwater quarry is an odd reminder of how far a storm can reach into the Keys.

The path passes native hammock trees including pigeon plum, gumbo limbo, and silver buttonwood. Poisonwood also grows nearby; its fruit feeds endangered white-crowned pigeons, but is toxic to people.