$16,000,000
1 E Sister Rck IsMarathon, FL 33050
Homes, condos and townhomes · MLS 11933144 · Listed 79 days ago (Aug 12, 2026)
Ocean or gulf · Direct parcel frontage · Waterfront details
For sale: Listed and available according to the MyStateMLS feed.
About this property
Own an entire private island in the Florida Keys, just 1/4 mile offshore from Marathon! East Sister Rock Island offers extraordinary privacy surrounded by turquoise waters, yet is only minutes from the mainland. The property encompasses approx. 6.5 acres, including approx. 5.8 acres of surrounding seabed, creating an exceptional marine setting for snorkeling, swimming, kayaking, paddleboarding, fishing and watersports. The beautifully updated 3-bedroom, 2-bath main residence and detached guest house offer over 5,000 total SF of living and entertaining space. Recent renovations include an updated kitchen with gorgeous countertops and modern finishes. A 12-ft-wide wraparound veranda captures panoramic water views, sunrises and spectacular Keys sunsets. Amenities include a waterfront pool and spa, tropical landscaping, outdoor entertaining areas, and a 100-ft deep-water dock. Self-sufficient infrastructure includes solar and wind power, battery storage, backup generator, desalination system and freshwater cistern capacity. Private helipad provides additional access. Seller is open to select Joint Venture opportunities.
Description provided by the listing brokerage.
MLS-reported waterfront
Waterfront details
The listing represents the offered parcel itself as adjoining the water. This is what the listing reports, not a survey or a title finding.
- Relationship to the water
- Direct parcel frontage
- Water type
- Ocean or gulf
- Water body
- Not provided. Ask the listing agent.
- Frontage length
- Not provided. Ask the listing agent.
- Water access arrangement
- Not provided. Ask the listing agent.
- Docks, slips, lifts, moorings
- Dock reported
- Dock depth
- Not provided. Ask the listing agent.
- Shoreline
- Not provided. Ask the listing agent.
- Seasonal or tidal conditions
- Not provided. Ask the listing agent.
- Boating limits (bridges, depth, open-water access)
- Not provided. Ask the listing agent.
The listing reports a dock. It does not say whether the dock is private, shared or transferable, or what boats it fits.
Why this is listed as waterfront
WaterfrontYN“Yes”: The listing is marked waterfront.WaterfrontFeatures“Ocean Front, Boat Dock”: Includes a "… Front" value describing frontage.PropertyTypeDetail“house”: Property form used to read the frontage relationship.
Classified from fields in the MyStateMLS listing data. It has not been independently verified, and it is not a survey, title examination or legal determination of shoreline or access rights. Rules version 2026-10-29.1. How we classify waterfront
Something wrong with this classification? Report a waterfront classification issue. Questions about frontage, docks or access are best answered by Compass Florida, LLC.
Facts
- List price
- $16,000,000
- Status
- For sale
- Property type
- House
- Bedrooms
- 4
- Full baths
- 3
- Interior area
- 2,304 sq ft
- Lot size
- 6.44 acres (280,628 sq ft)
- Year built
- 2015
- County
- Monroe County
- MLS number
- 11933144
- Annual property tax (2025)
- $25,482
Facts are reported by the listing brokerage. Items not listed were not provided; that does not mean the property lacks them.
Features
Exterior
- Dock
Appliances
- Washer
- Range
- Microwave
- Refrigerator
- Dryer
- Dishwasher
Flooring
- Tile
Heating
- Solar
Roof
- Metal
Sewer
- Septic Tank
Virtual tours
Location
The pin is the listing's reported coordinates and may be approximate. It is not a parcel boundary or shoreline, and no flood, wetland or hazard conclusion should be drawn from it. See more listings in Marathon.
Price and status history
Changes observed by Waterfront Homes in MyStateMLS data since Oct 29, 2026. This is not a public-record sales history; MyStateMLS does not publish sold prices.
Estimate a monthly payment
Estimated monthly payment
$87,695 per month
An estimate for comparison only, not a loan offer or approval. Actual rates, taxes, insurance, PMI and fees depend on your lender, credit, location and loan program.
Questions to ask before you buy
Questions worth investigating for any waterfront property. They are not claims that this property has a problem or meets any condition.
- Who owns the shoreline and the land under the water, and are there easements or public-access rights along it?Ownership can stop at a high-water line, a survey line or a seawall. A title search and survey answer this, not the listing.
- Is a dock, slip, lift or mooring included, and do the rights transfer to you?Docks can be shared, leased, assigned by an association or held under a permit that does not automatically transfer.
- What permits exist for the dock, seawall or other shoreline structures, and what would new work require?Shoreline work is often regulated by local, state and federal agencies.
- How much does the water level change by season, by tide or by reservoir management?Depth at a dock in one season can differ a lot in another.
- What does flood insurance cost for this property, and what does the current flood map show?Get a quote from an insurer or agent. A flood zone is not a premium, and no zone does not mean no risk.
- What maintenance does the shoreline need (seawall, bulkhead, riprap, erosion), and what has been done recently?Shoreline structures are expensive to repair; ask for records and inspection reports.
- How are water, sewer or septic, and power provided?Waterfront septic systems and wells can have extra rules and inspections.
- How do you reach the property by road year-round, and who maintains that road?Some waterfront roads are private, seasonal or shared.
- What local rules apply: rentals, docks, boat lifts, fences, tree removal, setbacks?Rules come from the town, county, state, lake authority or association and vary widely.
Printable due-diligence checklist · Ownership budget planner · FEMA Flood Map Service Center (official flood maps; look up the address yourself)
Guides and next steps
Listing courtesy of Compass Florida, LLC. Listings provided by MyStateMLS.
Listing last updated by the brokerage Sep 17, 2026, 12:50 PM UTC. Waterfront Homes last received MyStateMLS data Oct 30, 2026, 6:01 PM UTC. Information is deemed reliable but not guaranteed; verify all details with the listing agent.