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.
Listing Provided Courtesy of Coldwell Banker at 561-395-2233
Property Details
Price:
$18,500,000
MLS #:
B26058354
Status:
Active
Beds:
4
Baths:
4.5
Type:
Single Family
Subtype:
Single Family Residence
Subdivision:
MASHTA ISLAND
Neighborhood:
2520
Listed Date:
Jul 30, 2026
Finished Sq Ft:
2,255
Total Sq Ft:
3,720
Lot Size:
653,400,000 sqft / 0.34 acres (approx)
Year Built:
1958
See this Listing
Schools
Elementary School:
Key Biscayne K-8
Middle School:
Ponce De Leon
High School:
Coral Gables
Interior
Appliances
Electric Water Heater, Wine Refrigerator, Electric Cooktop, Cooktop, Dishwasher, Dryer, ENERGY STAR Qualified Dishwasher, ENERGY STAR Qualified Dryer, ENERGY STAR Qualified Freezer, ENERGY STAR Qualified Refrigerator, ENERGY STAR Qualified Washer, Free-Standing Freezer, Microwave, Oven, Refrigerator, Washer, Water Heater
Bathrooms
4 Full Bathrooms, 1 Half Bathroom
Cooling
Central Air
Flooring
Concrete, Laminate, Tile
Heating
Central, Electric
Interior Features
Entrance Foyer, Walk-In Closet(s)
Laundry Features
Inside, Laundry Room, Sink
Main Level Bathrooms
4
Main Level Bedrooms
4
Exterior
Construction Materials
Brick, Concrete
Covered Spaces
2
Direction Faces
East
Exterior Features
Garden, Private Rooftop Terrace
Green Energy Efficient
Appliances, HVAC
Open Parking Spaces
6
Parking Features
Attached Carport, Carport, Circular Driveway, Driveway
Parking Spots
8
Parking Total
8
Patio And Porch Features
Patio – Open, Patio – Covered, Patio
Roof
Shingle
Stories
1
View
Intracoastal, Bay, Pool, Water
Waterfront Features
No Fixed Bridge, Ocean Access, Bay, Intracoastal, Navigable Water, Seawall
Window Features
Storm Window(s)
Financial
Tax Year
2025
Taxes
$112,485
Map
Community
- Address631 N Mashta Drive Key Biscayne FL
- SubdivisionMASHTA ISLAND
- CityKey Biscayne
- CountyMiami-Dade
- Zip Code33149
Subdivisions in Key Biscayne
Market Summary
Current real estate data for Single Family in Key Biscayne as of Aug 01, 2026
2
Single Family Listed
68
Avg DOM
4,688
Avg $ / SqFt
$11,725,000
Avg List Price
Property Summary
- Located in the MASHTA ISLAND subdivision, 631 N Mashta Drive Key Biscayne FL is a Single Family for sale in Key Biscayne, FL, 33149. It is listed for $18,500,000 and features 4 beds, 5 baths, and has approximately 2,255 square feet of living space, and was originally constructed in 1958. The current price per square foot is $8,204. The average price per square foot for Single Family listings in Key Biscayne is $4,688. The average listing price for Single Family in Key Biscayne is $11,725,000.
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