East Sister Rock — A Private Island Off Marathon in the Keys

$16M buys you an entire island. 🏝️

East Sister Rock Island sits a quarter mile off Marathon in the Florida Keys — a 6.44-acre private island where roughly 5.8 acres of that is the seabed around it. The water is yours. Snorkeling, kayaking, paddleboarding, fishing, all of it off your own shoreline, with the mainland minutes away by boat. A 12-ft wraparound veranda wraps the residence for sunrise on one side and Keys sunsets on the other.

The ultimate flex? You don't need the mainland at all. Solar and wind power, battery storage, a backup generator, a desalination system and freshwater cistern capacity make the island fully self-sufficient. A 100-ft deep-water dock handles the boat. The private helipad handles everything else.

The Specs:

📍 1 E Sister Rock Is, Marathon, FL
💰 $16,000,000
📐 5,000+ sq ft total · 6.44-acre private island
🛏️ 4 beds · 3 baths across main house + guest house
🚁 Private helipad
⚓ 100-ft deep-water dock
🌊 Waterfront pool and spa