MASHTA ISLAND
631 N Mashta Drive, Key Biscayne FL 33149
4 beds · 4.5 baths · 2,255 ft²
$18,500,000
Est. Payment $98,465/mo
4
Bedrooms
4.5
Bathrooms
2,255
Sq. Ft.
1958
Year Built
1
Stories
2
Days on Market
Description
BRING ALL OFFERS! Exceptional waterfront opportunity in prestigious Key Biscayne. Set on a 15,000 sq. ft. lot with 100 feet of water frontage, this residence offers open-water views, direct Biscayne Bay access, and no fixed bridges to the ocean. Currently undergoing a complete renovation, it will feature modern finishes, impact windows and doors, new systems, spacious living areas, a chef's kitchen, and luxurious bathrooms. Enjoy a private dock, deep-water access, pool, breathtaking sunsets, and an unmatched boating lifestyle in one of South Florida's most desirable communities One of the most compelling waterfront opportunities currently available in all of Key Biscayne. Perfectly positioned on the exclusive and highly coveted Mashta Island, this exceptional property offers approximately 100 feet of prime waterfront, deep-water dockage, direct Biscayne Bay access, and no fixed bridges to the Atlantic Ocean, creating an unparalleled opportunity for boating enthusiasts and yacht owners. Mashta Island has long been recognized as one of South Florida's most prestigious residential enclaves, offering exceptional privacy, quiet tree-lined streets, oversized waterfront estates, and immediate access to the open waters of Biscayne Bay while remaining only minutes from Brickell, Downtown Miami, Coconut Grove, Coral Gables, Miami Beach, and Miami International Airport. Very few neighborhoods offer this combination of island living, security, boating lifestyle, and proximity to the city's financial and cultural centers. The residence is currently on renovation designed to transform the property into a contemporary waterfront estate while preserving the exceptional value of its location and oversized waterfront parcel. This is substantially more than a cosmetic renovation. The project includes major improvements throughout the residence, including redesigned living spaces, upgraded electrical and plumbing systems, new HVAC equipment, impact-resistant windows and doors, premium flooring, modern architectural lighting, designer finishes, and a completely reimagined interior intended to meet today's luxury lifestyle expectations. Upon completion, the home is anticipated to offer spacious entertaining areas, beautifully appointed bedroom suites, bathrooms, an impressive chef's kitchen featuring custom cabinetry, premium appliances, elegant countertops, and thoughtfully designed indoor-outdoor living spaces that maximize the spectacular waterfront setting. The property's exceptional orientation provides beautiful water views and unforgettable sunsets while creating an ideal environment for entertaining, family gatherings, and year-round outdoor living. The expansive backyard offers generous space surrounding the swimming pool together with multiple areas for outdoor dining, lounging, and enjoying the waterfront lifestyle that has made Key Biscayne one of the most desirable residential communities in South Florida. For boating enthusiasts, few properties can offer the combination of oversized waterfront, private dockage, deep-water access, and unrestricted navigation to Biscayne Bay and the Atlantic Ocean without fixed bridges. Whether accommodating a large sport yacht, cruising yacht, center console, or multiple vessels, the waterfront configuration provides flexibility rarely available in today's market. Key Biscayne continues to be recognized as one of South Florida's most exclusive island communities, celebrated for its pristine beaches, excellent schools, private clubs, marinas, tennis facilities, parks, bicycle paths, restaurants, and relaxed coastal lifestyle. Residents enjoy the unique advantage of living within a peaceful island environment while remaining only a short drive from Miami's world-class shopping, fine dining, cultural institutions, private airports, international business centers, and professional sports venues. The supply of premium waterfront homes on Mashta Island remains extremely limited due to the neighborhood's established character and finite number of waterfront parcels. As a result, opportunities to acquire large waterfront lots with substantial dockage and direct ocean access continue to be highly sought after by both domestic and international buyers. The combination of location, waterfront dimensions, boating accessibility, oversized lot, and comprehensive renovation creates a property with exceptional long-term appeal. Showings are strictly by appointment with the Listing Agent.. All measurements, dimensions, lot size, square footage, waterfront frontage, dock dimensions, room sizes, zoning, taxes, permits, specifications, plans, renderings, and property information are believed to be accurate but are not guaranteed and should be independently verified by Buyer. Renderings, conceptual plans, floor plans, specifications, and construction updates are available upon request when applicable. This offering represents an extraordinary opportunity to secure one of Key Biscayne's waterfront residences . Whether as a primary residence, seasonal retreat, or long-term investment, this property combines one of South Florida's most desirable locations with an outstanding boating lifestyle and exceptional future value. Bring All Offers.
Facts
- MLS#
- B26058354
- Subdivision
- MASHTA ISLAND
- Property Type
- Residential
- Property Sub Type
- Single Family Residence
- Year Built
- 1958
- Lot Size
- 14,810 ft²
- Sq. Ft.
- 2,255 ft²
- Sq. Mt.
- 209 m²
- Price per sq. ft.
- $8,204/ft²
- Price per sq. mt.
- $88,517/m²
- Stories
- 1
- Garage
- —
- Pool
- Private
- Days on Market
- 2 days
- Listed
- Jul 29, 2026
- Last Updated
- Jul 31, 2026
- Price/Lot Sq.Ft.
- $1,249/ft²
Comparable homes
Same ZIP, similar price + bedrooms.
SOLD$17,200,000
4 bd · 4 ba · 3,085 sqft
520 S MASHTA DR, Key Biscayne FL 33149

$16,800,000
4 bd · 4 ba · 3,620 sqft
640 S Mashta Dr, Key Biscayne FL 33149
SOLD$21,000,000
4 bd · 4 ba · 2,566 sqft
200 Harbor Dr, Key Biscayne FL 33149
SOLD$22,000,000
3 bd · 3 ba · 1,806 sqft
398 Harbor Dr, Key Biscayne FL 33149
SOLD$14,900,000
5 bd · 6 ba · 7,004 sqft
260 Harbor Dr, Key Biscayne FL 33149
Market insights for Key Biscayne
Live MLS-derived activity. Forecast is a conservative rule-of-thumb estimate — not a guarantee.
Sellers market
August 2026
58
Median days to sold
+4.5%
1-year price forecast (est.)
Price & tax history
From the live MIAMI MLS feed. Older history requires the ListingHistory resource (not yet enabled).
| 7/29/2026 | Listed for sale | $18,500,000 |
History reflects fields present on the live MLS record. Full multi-year history requires the MIAMI ListingHistory resource (not yet enabled).
Location
GreatSchools Summary Ratings
Public + private K-12 schools within 5 miles of this listing.
Waldorf International SchoolPK,KG,1,2,3,4,5 · private · 0.7 mi
Whispering Pines Elementary SchoolPK,KG,1,2,3,4,5 · public · 1.0 mi
Cutler Bay Senior High School9,10,11,12 · public · 1.1 mi
Kid's Club AcademyPK,KG,1 · private · 1.3 mi
Palmer Trinity School6,7,8,9,10,11,12 · private · 1.4 mi
Dr. Edward L. Whigham Elementary SchoolPK,KG,1,2,3,4,5 · public · 1.5 mi
Wonderful Paradise Learning Center I3 · private · 1.5 mi
Cutler Ridge Umc KindergartenPK,KG · private · 1.5 mi
Mater Academy Bay ElementaryKG,1,2,3,4,5 · charter · 1.7 mi
Mater Academy Bay Middle School6,7,8 · charter · 1.7 mi
Estimated Monthly Payment
$114,031/mo
Principal & Interest
$98,465
Property Tax
$15,417
Insurance
$150
HOA
$0
Estimates only. Actual payment depends on credit, lender, insurance carrier, and FL/Miami-Dade specifics. Contact Rangely for a precise quote.
The data relating to real estate for sale on this website comes in part from the Southeast Florida Multiple Listing Service. MLS Data is deemed reliable, but is not guaranteed accurate by MIAMI REALTORS®.
Accuracy of listing information is not guaranteed. Listing information is provided for personal consumer, non-commercial use, solely to identify potential properties for potential purchase. All other use is strictly prohibited and may be a violation of federal and state law.
Copyright Southeast Florida MLS a/k/a SEFMLS © 2026.
Updated within 24 hours
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