House in Key Biscayne, FL 33149Mashta Island, 631 N Mashta Dr






$18,500,000
4
Beds41/2
Baths2,255
SqFt$8,204
$/SqFtUltra Luxury HouseProperty Type
1958Year Built
$8,204/SqFtPrice per sq ft
Bay, Intercoastal, Pool, WaterView
YesWaterfront
GardenExterior Features
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 Courtesy Of: Coldwell Banker
Local Realty Services Provided By: Best of Luxury Realty
On Site: 91 DaysUpdated: 3 Days agoPage Views: 0
Features
MLS Number: B26058354
Bedrooms
- Bedrooms: 4
Bathrooms
- Bathrooms: 4
- Half Bathrooms: 1
Exterior and Lot Features
- Exterior Features: Garden, OutdoorLivingArea
- View: Bay, Intercoastal, Pool, Water
Interior, Heating and Cooling
- Interior Features: DualSinks, EntranceFoyer, LivingDiningRoom, WalkInClosets
- Equipment / Appliances: Cooktop, Dryer, Dishwasher, EnergyStarQualifiedDishwasher, EnergyStarQualifiedDryer, EnergyStarQualifiedFreezer, EnergyStarQualifiedRefrigerator, EnergyStarQualifiedWasher, ElectricCooktop, ElectricWaterHeater, FreeStandingFreezer, Microwave, Oven, Refrigerator, WaterHeater, WineRefrigerator, Washer
- Heating Description: Central,Electric
- Cooling Description: CentralAir
Building and Construction
- Floor Description: Concrete, Laminate, Tile
- Windows/Treatment: StormWindows
- Construction Type: House
- Year Built: 1958
Waterfront and Water Access
- Waterfront Frontage: Yes
School Information
- Elementary School: Key Biscayne K-8
- Middle School: Ponce De Leon
- Senior High School: Coral Gables
Other Property Info
- Listing Date: 2026-07-30T14:40:51.000-00:00
- Directions: East
- Pets Allowed: NoPetRestrictions, Yes
Taxes, Fees & More
- Taxes: 112485
- Parking Description: AttachedCarport, CircularDriveway, Carport, Driveway
- Total Floors in Building: 1
Apples-to-Apples Comparables
Price History
Date
Event
Price
Change
Price Per
07/30/2026
Listed
$18.5M
$8,204 ft2
$88,308 m2
07/30/2026
$18.5M
Event
Listed
Price Per
$8,204 ft2
$88,308 m2
Price per square foot and days on website are not provided values and are calculated by Subdivisions.
Listed by Javier Quiroz • Coldwell Banker • Buyer Agency Compensation .
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Community Snapshot
4 – 5 BR
Bedrooms
$6.4M – $19.9M
Price Tier
2,255 - 10,820
SqFt Range
1972
Year Build
1
Total Floors
71
Total Units
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