ActiveWaterfront
$18,500,000
631 N Mashta Drive, Key Biscayne, FL 33149
Listed by Coldwell Banker
Key Biscayne · Luxury
Luxury Homes for Sale in Key Biscayne, FL
Key Biscayne is an island with one road on and off it. That single fact shapes the supply, the insurance math and how the village governs what gets rebuilt.
Luxury listings
Luxury homes for sale in Key Biscayne right now
ActiveWaterfront
$18,500,000
631 N Mashta Drive, Key Biscayne, FL 33149
Listed by Coldwell Banker
Active
$4,950,000
24 Grand Bay Estates Circle, Key Biscayne, FL 33149
Listed by Engel & Voelkers Vero Beach
See all 2 homes in Key Biscayne
Copyright Southeast Florida MLS a/k/a SEFMLS © 2026. Accuracy of listing information is not guaranteed. Listing information is provided for personal consumer, non-commercial use, solely to identify potential properties for potential purchase. All other use is strictly prohibited and may be a violation of federal and state law. MLS data is deemed reliable but is not guaranteed accurate by MIAMI REALTORS®.
Copyright Southeast Florida MLS a/k/a SEFMLS © 2026. Accuracy of listing information is not guaranteed. Listing information is provided for personal consumer, non-commercial use, solely to identify potential properties for potential purchase. All other use is strictly prohibited and may be a violation of federal and state law.
MLS data is deemed reliable but is not guaranteed accurate by MIAMI REALTORS®.
Equal Housing Opportunity. All real estate advertised is subject to the Federal Fair Housing Act.
Market snapshot
2 active listings at $3,000,000 and up
Highest asking price right now: $18,500,000
Straight from the MLS feed on this page. It moves when the feed moves, and it is the only market number I publish here.
Where the luxury homes are
Harbor Drive and the canal streets The island's canal system on the bay side, where lots carry private dockage and a short run into Biscayne Bay. Mostly mid-century houses, steadily replaced with new construction on the same parcels.
Mashta Island A small bridged island at the south end of the village, with wide water frontage, larger parcels and a street pattern with no through traffic.
The ocean corridor Ocean Drive and Ocean Lane Drive along the Atlantic side, where low-rise and mid-rise buildings from the 1960s onward sit on direct beach frontage with a handful of single lot houses between them.
The village center grid The blocks around Crandon Boulevard, where lot sizes are smaller and the houses date from the 1950s and 1960s, with rebuilding happening lot by lot under village review.
Cape Florida and the south end The streets closest to Bill Baggs at the tip of the island, a mix of gated parcels and beach access lots, as far from the causeway as the island goes.
Key Biscayne is an island reached by the Rickenbacker Causeway, with Crandon Park at its north end and Bill Baggs at its south, and the Village of Key Biscayne occupying everything in between. The island is built out, so nothing here is new land. What trades is the existing platting: ocean frontage on the Atlantic side, canal and bay frontage on the Harbor Drive streets and Mashta Island, and the older village grid in the middle.
That makes this a market about rebuilding rights as much as about houses. I read the village code against the survey, the flood zone against the elevation certificate, and the shoreline against what the preserve permitting will actually allow. On the water I check depth at the seawall at low tide, because on a barrier island the number in the remarks and the number under your hull are rarely the same.
What to check before you buy
What to check before you buy
Access, the causeway, and what that means in a storm
One road connects the island to the mainland. That shapes evacuation planning, how a closure affects you and how insurers price the address. I would rather you understand it before you own it than after.
Dock permitting inside the aquatic preserve
The bay side sits in a protected preserve, where seagrass, setbacks and length limits govern what can be built or rebuilt at the shoreline. An existing dock is not proof of what you would be allowed to build again.
Village zoning on a teardown or a major rebuild
The village regulates height, lot coverage and setbacks tightly, and those rules decide whether the house you have in mind fits the parcel. I read the code against the survey before you pay for architectural drawings.
Elevation, flood zone and a bound insurance quote
This is a barrier island and the elevation varies street to street. I want the elevation certificate for the specific house and a real quote inside the inspection period, because that number is part of your purchase price.
Depth at the seawall and the route into the bay
On the canal streets, depth at low tide and turning room decide what can actually live at the dock. I check the water at low tide rather than reading the number out of the listing remarks.
FAQ
Key Biscayne luxury questions
What sits at the top of the Key Biscayne market?
Direct ocean frontage and the widest bay frontage, principally on Mashta Island and the outer canal lots, where parcels are largest and the water opens quickly. Frontage and parcel size set the ceiling here. The live numbers above come from the MLS feed.
How do you get to the island?
By the Rickenbacker Causeway from Miami, and that is the only road. It passes Virginia Key on the way, with Crandon Park at the north end of the village and Bill Baggs at the south end. Everything on the island sits between those two parks.
Can I keep a boat at the house?
On the canal streets and on the wider bay frontage, yes, subject to the preserve permitting. The run into Biscayne Bay is short and open. Tell me the length and draft first, because depth at the seawall varies more than you would expect on an island this small.
House or condominium at this price?
Both exist here. The ocean corridor buildings trade on the line, the view and the association's funding record. The canal and island parcels trade on frontage, dockage and what the village will let you rebuild. They are different purchases with different diligence.
Is there new construction on the key?
Yes, but it happens one parcel at a time within the existing platting rather than in new subdivisions, because the island is built out. That is why the zoning review matters so much to anyone buying with a rebuild in mind.
Let us talk
Shopping Key Biscayne at this level?
Tell me the budget and the must-haves. I will send the homes that fit, with the water, the building, and the carrying costs checked before you see them, in English o en español.