520 Mashta Drive, Key Biscayne, FL 33149

$18,500,000 — Active

Property Features

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Seize a rare opportunity to create a landmark waterfront estate on one of the largest residential lots in Key Biscayne’s exclusive Mashta Island enclave. Spanning an extraordinary 22,140 square feet, this exceptional property offers 138 feet of pristine water frontage and sweeping open water views, providing an unparalleled setting for a world class residence.Plans by renowned architect, Pablo Corazzini of Vitalini Corazzini Architects, are available to the buyer, offering a thoughtfully conceived vision that takes full advantage of the property’s remarkable scale, premier waterfront setting, and spectacular sunsets. The proposed design creates an extraordinary canvas for sophisticated indoor-outdoor living and entertaining, should the buyer choose to pursue the concept.With its exceptional lot size, expansive water frontage, and coveted Mashta Island address, this is a truly irreplaceable opportunity to create a legacy estate in one of South Florida’s most prestigious waterfront communities.

▼ Price Reduced — originally listed at $19,900,000

Property Details

  • Listing ID: A12071221
  • Status: Active
  • Listing Date: 2026-08-12
  • Property Type: Single Family Residence
  • Subdivision: MASHTA ISLAND A REPLAT OF
  • County: Miami-Dade
  • MLS Area: 2520
  • Bedrooms: 5
  • Full Bathrooms: 4
  • Living Area Sq Ft: 3,085
  • Year Built: 1961

Financial

  • List Price: $18,500,000
  • Original List Price: $19,900,000
  • HOA Fee: None
  • Taxes: $201,741/yr

Features & Amenities

  • View: Bay, Direct Ocean
  • Parking: Driveway
  • Cooling: Central Air
  • Heating: Central
  • Flooring: Tile
  • Construction: Block
  • Roof: Barrel, Spanish Tile
  • Interior Features: Bedroom Layout - Split
  • Community Amenities: Other

Courtesy of Coldwell Banker Realty
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© 2026 Starfish Real Estate. Listings updated Nov 8, 2026 2:03 am. Listing data is derived from the Broker Reciprocity Program of the Realtor Association of Indian River County (RAIRC) and BeachsMLS. Properties listed by brokers other than Starfish Real Estate are identified with the applicable MLS logo and include the listing broker's name. Not all properties available through either MLS may be displayed. All MLS data is the copyrighted property of the respective MLS and its participants. Data is deemed reliable but is not guaranteed accurate and should be independently verified prior to entering into any transaction.