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631 N Mashta Drive, Key Biscayne FL 33149

House For Sale
$18,500,000

BTC: 287.26708075

ETH: 9,723.33179162

2 days
Waterfront
4 bds
4 ba
2,255 sqft

Overview

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.

Location

Details

Type:
Residential
Parking:
2 Or More Spaces / Circular Driveway / Driveway
Year Built:
1958
Lot:
0.34 Acres
Heating:
Central / Electric
Price/sqft:
$8,204
Cooling:
Central Air
HOA:
No Data

Valuation

Our model vs. what's actually selling nearby.
Estimate
$2,592,500
$1.3M – $9.0M
Confidence Low
List vs. estimate
$15.9M above estimate
List $18,500,000 · +613.6%
Our model says this listing is priced above recent comparable activity. Room to negotiate.
Price per sq ft
$8,203
+326.0% vs. city median $1,925
Based on
8 MLS comparables
+ 12 public-records sales within 0.5 mi
Median actual sale: $3.6M
Median of recent comparable listings. Sold comps use closing price, active listings use list price.

Highlights

Annual tax
$112,485
2025
Pool
Equipment Stays
View
Bay, Intracoastal View
Waterfront
Intracoastal Front, Navigable Water
Parking
8 spaces
Pets
Allowed
All facts and features
  • Flooring

    • Concrete

    • Tile

    Heating

    • Central

    • Electric

    Cooling

    • Central Air

    Appliances

    • Electric Water Heater

    • Dishwasher

    • Dryer

    • Free-Standing Freezer

    • Microwave

    • Refrigerator

    • Self Cleaning Oven

    • Wall Oven

    • Washer

    Other interior features

    • Entrance Foyer

    • Walk-In Closet(s)

    Bedrooms and bathrooms

    • Bedrooms: 4

    • Bathrooms: 1

    • Full bathrooms: 4

  • Parking

    • 2 Or More Spaces

    • Circular Driveway

    • Driveway

    Property

    • Levels: 1

    • Pool Private: Yes

    Lot

    • Lot: 0.34 Acres

    Other Property Information

    • Parcel Number: 24-52-05-008-0070

    • Zoning: 2001

  • Type and style

    • Property Type: Residential

    • Property Sub Type: Single Family Residence

  • Utility

    • Electricity Available

    • Sewer Available

    • Water Available

    Green energy

    • Appliances

    • HVAC

  • Other financial information

    • Annual tax amount: $112,485

  • Source details

    • MLS ID: B26058354

    Other facts

    • Construction Materials: Concrete Block Construction / Brick

    • Lot Features: 1/4 To Less Than 1/2 Acre Lot / Less Than 1 Acre

    • Patio And Porch Features: Patio

    • Pool Features: Equipment Stays

    • Window Features: Complete Impact Glass

    • Direction Faces: East

    • Other Structures: Livable

    • Waterfront: Yes

    • Attached Garage: Yes

    • Living Area: 2255

    • Water Source: Public

    • Subdivision Name: MASHTA ISLAND

Private inquiry
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The multiple listing information is provided by the Miami Association of REALTORS® from a copyrighted compilation of listings. The compilation of listings and each individual listing are ©2026-present Miami Association of REALTORS®. All Rights Reserved. The information provided is for consumers' personal, noncommercial use and may not be used for any purpose other than to identify prospective properties consumers may be interested in purchasing. All properties are subject to prior sale or withdrawal. All information provided is deemed reliable but is not guaranteed accurate, and should be independently verified. Listing courtesy of: Coldwell Banker