640 S Mashta Dr

Key Biscayne, FL 33149

$16,800,000

$4,641/ft²

4Beds

4Baths

3,620Sq ft

1968Year built

Single-family homeType

About this home

Welcome to your own slice of paradise! Enjoy breathtaking sunsets from your private dock on this waterfront property boasting 100 feet of direct Biscayne Bay frontage. Ideally located on Mashta Island. Set on a 15,000 SF lot, the home features 5 beds, 5 baths, including 2 bayfront primary suites with stunning views, impact windows and doors throughout. The open-concept layout flows seamlessly from the living and dining areas to the modern kitchen and out to the pool and entertainment patio, with floor-to-ceiling glass doors that open to blend indoor and outdoor living. Tranquil guest suite upstairs offering privacy and views. It also features an oversized 2-car garage, covered parking, and a spacious driveway for guests. Perfect to move in, renovate, or build your dream waterfront estate

Features

Waterfront

Property details

Listing

MLS #: A11990382
Status: For sale
Listed on: Apr 2, 2026
Days on market: 129 days
Listing data updated: Apr 5, 2026

Interior

Beds: 4
Baths: 4
Living area: 3,620 ft²
Price per ft²: $4,641/ft²

Building & community

Type: Single-family home
Year built: 1968
County: Miami-Dade

Lot & exterior

Lot size: 15,000 ft²
Waterfront: Yes

Days on market, price per ft² and the monthly HOA amount are calculated by this site from the MLS data shown; the association fee is normalized to a monthly figure.

True monthly cost

Mortgage (principal & interest): $84,950
Property taxes (est.): $15,400
Home insurance (est.): $600
Flood insurance (est.): —

Estimated total$100,950*/mo

* Some cost lines aren't available yet for this listing; the total shown is incomplete.

Based on 20% down, a 6.5% rate and a 30-year loan, plus this home's estimated Florida carrying costs. All figures are illustrative estimates — not quotes, not financial or insurance advice.

Sources: flood zone — FEMA National Flood Hazard Layer; mortgage, taxes and insurance figures — this site's own estimates; HOA / CDD — as reported for this listing.

What will this home really cost you?