1 E Sister Rck Is

Marathon, FL 33050

$16,000,000

$6,944/ft²

4Beds

3Baths

2,304Sq ft

2015Year built

Single-family homeType

About this home

Own an entire private island in the Florida Keys, just ¼ 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.

Features

Waterfront

Property details

Listing

MLS #: A12069701
Status: For sale
Listed on: Aug 12, 2026
Days on market: 15 days
Listing data updated: Aug 12, 2026

Interior

Beds: 4
Baths: 3
Living area: 2,304 ft²
Price per ft²: $6,944/ft²

Building & community

Type: Single-family home
Year built: 2015
County: Monroe

Lot & exterior

Lot size: 280,628 ft²
Waterfront: Yes

Days on market, price per ft² and the monthly HOA amount are calculated by this site from the MLS data shown; the association fee is normalized to a monthly figure.

What's nearby

Transit: MILE MARKER 50 MARATHON · 2 mi away

Straight-line distances · Sources: NCES/FL DOE, GTFS Miami-Dade and Broward, OpenStreetMap

True monthly cost

Mortgage (principal & interest): $80,905
Property taxes (est.): $14,667
Home insurance (est.): $12,000
Flood insurance (est.): —

Estimated total$107,572*/mo

* Some cost lines aren't available yet for this listing; the total shown is incomplete.

Based on 20% down, a 6.5% rate and a 30-year loan, plus this home's estimated Florida carrying costs. All figures are illustrative estimates — not quotes, not financial or insurance advice.

Sources: flood zone — FEMA National Flood Hazard Layer; mortgage, taxes and insurance figures — this site's own estimates; HOA / CDD — as reported for this listing.

What will this home really cost you?