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1 E Sister Rock Island
Marathon, FL, 33050
Active$16,000,000
1 E Sister Rock Island
Marathon, FL, 33050
Active$16,000,000
4
Bedrooms
3
Bathrooms
2,304 sqft
Living Area
1980
Year Built
280,526
Lot Size (sqft)
1
Days on Market
Dock Score™
DockOnly38
FairWhat shaped this score
✓Dock present
✓Bridge-free to ocean
✓deep water, private dock
·Waterfront
DockOnly.com rating, not provided by the MLS or listing broker.
Dock & Water AccessMLS
Oceanfront📝 deep water
AI Aerial Imagery Detection
Dock DetectedDeep Water Indicators
Detected by AI from open-source aerial mapping imagery and may not reflect current conditions. This information was not provided by the MLS or listing broker. Always verify dock infrastructure with the listing agent.
Navigation RouteDockOnly
Data sources: SFWMD AHED waterway polygons · FHWA National Bridge Inventory 2024 · Not provided by the MLS or listing broker.
Description
Own an entire private island in the heart of the Florida Keys. Located just ¼ mile offshore from Marathon, East Sister Rock Island offers extraordinary privacy surrounded by turquoise waters, yet remains only minutes from the mainland. The property encompasses approximately 6.5 acres, including approximately 5.8 acres of surrounding seabed that create an exceptional marine setting for snorkeling, swimming, kayaking, paddle boarding, fishing and exploring the crystal-clear waters of the Keys. At the center of the island is a beautifully updated 3-bedroom, 2-bath main residence with a detached guest house, offering over 5,000 total SF of living and entertaining space. Recent interior renovations include a beautifully updated kitchen with gorgeous countertops and modern finishes. A 12-foot-wide wraparound veranda captures panoramic water views, Atlantic sunrises and spectacular Florida Keys sunsets. Designed for the ultimate island lifestyle, the property features a waterfront pool and spa, tropical landscaping, multiple outdoor lounging and dining areas, and a 100-foot deep-water dock with ample dockage. World-class fishing, diving, snorkeling, boating and water-sports begin just outside your door. East Sister Rock is equipped for self-sufficient island living with solar and wind power, battery storage, backup generator, desalination system and substantial freshwater cistern capacity. A private helipad provides an additional point of access. Few properties offer this combination of privacy, accessibility, marine surroundings and established island infrastructure. Seller is also open to exploring select Joint Venture opportunities. Note the sale includes 99 E Ocean Drive on the mainland which has a private dock space.
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Location
Marathon, FL, 33050
No price history available for this property.
Displayed by Blue Mar Real Estate Group Inc., Licensed Florida Real Estate Broker (DBPR CQ1018554) · [email protected]
Listing courtesy of Compass Florida, LLC via Florida Keys MLS
Last checked: 4 hours ago
Listing updated: August 13, 2026
© 2026 Florida Keys Board of REALTORS®, Inc. All rights reserved. The data relating to real estate for sale on this website comes in part from the Internet Data Exchange (IDX) program of the Florida Keys Board of REALTORS®. Information is deemed reliable but not guaranteed and should be independently verified. All properties are subject to prior sale, change, or withdrawal.
IDX information is provided exclusively for consumers' personal, non-commercial use. It may not be used for any purpose other than to identify prospective properties consumers may be interested in purchasing.
Dock Score™
DockOnly38
FairWhat shaped this score
✓Dock present
✓Bridge-free to ocean
✓deep water, private dock
·Waterfront
DockOnly.com rating, not provided by the MLS or listing broker.
Nearest Bridge Clearances
Florida Keys, critical for tall/large vessels
No bridge data available for this location.
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Mortgage Calculator
Estimate your monthly payment for this waterfront property
20%
$3,200,000 down
%
Principal & Interest$83,021/mo
Property Tax (est. ~1.2%, varies by county)$16,000/mo
Home Insurance (est.)$250/mo
Total Monthly Payment$99,271
Loan Amount: $12,800,000Rate: 6.75%
Get Pre-QualifiedEstimated payments only. Actual rates and terms may vary.
Navigation note: Navigation routes show the shortest mapped path to open water. A vessel taller than the binding bridge clearance may still reach open water via a longer alternate route that we don't currently map. Verify navigability with a local captain or surveyor before relying on it.