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Single Family ResidenceResidential
$9,999,999$2,407 / ft²
TopHap EstimateOur estimate of what this home would sell for today, based on nearby sales, the home's size and features, and local price trends. It is a starting point, not an appraisal.· confidence 91How well the pricing models agreed with each other on this home. Higher means the estimate rests on stronger, more consistent data.· as of Sep 24, 2026
Last sold for $1,350,000 on Nov 5, 1999

999 MARINER DR

KEY BISCAYNE, FL 33149
4
Beds
3 / 1
Baths
4,155 ft²
Living AreaTotal finished area of the structures, from county records. Some counties include shared space like hallways or a building gym, so it may not match a listing.
0.36 ac
Lot SizeThe size of the land the home sits on, from county records.
1973
Year BuiltThe year the home was originally built, according to county records.
1
StoriesHow many floors the home has above ground.

Valuation

$10M
$10M low$10M high
Last SaleThe most recent sale price and date from the recorded deed. Transfers between family members or companies may not reflect market value.$1,350,000 · Nov 5, 1999

Tax & Assessment

Property TaxThe property tax billed for this tax year. It usually pays for schools, roads, and local services.$34,478 (2024)
Assessed ValueThe value the county assigns to this home to calculate property tax. It is often lower than what the home would sell for.$2,122,820 (2024)
Previous AssessedThe county's assessed value from the year before, useful for seeing how the assessment changed.$2,060,991
Assessor Market ValueThe county assessor's own opinion of market value. It is separate from our estimate and updates on the county's schedule.$7,003,321

Climate Risk

Projected Flood DepthHow deep a serious flood is expected to get here at some point in the next 30 years. Shown in inches.58 in
30-Year Flood ChanceThe chance of at least one serious flood here in the next 30 years, not in any single year.100%
FEMA Flood ZoneFEMA's flood zone for this address. Zones starting with A or V are high risk, and lenders usually require flood insurance there.1 percent flood zone

Scores 0–100; higher = greater projected risk.

Property Facts

Property TypeThe broad category the county puts this property in, such as residential or commercial.Single Family Residence
CountyMiami-Dade
Effective Year BuiltAn adjusted build year that accounts for condition and major remodels. A big renovation can make a home count as newer than it is.2001
Lot (acres)The size of the land the home sits on, from county records.0.36
ConstructionThe main material the home's frame and walls are built from.Concrete
HeatingThe type of heating system in the home.None
PoolWhether the property has a pool, and what kind, such as in-ground.Yes
FeaturesExtra features found in county records. Records are not complete everywhere, so a missing feature does not always mean the home lacks it.GazeboPatio · 401 ft²Porch · 485 ft²Boat access

Transaction History(1)

Sales and refinances filed with the county for this home. Not every transfer is a normal sale, so check the type before comparing prices.

Assigned SchoolsThe public schools this address is zoned for. Boundaries change, so confirm with the district before you count on it.

E
Key Biscayne K-8 CenterA-
Elementary · Grades PK–5 · 0.4 mi
M
Ponce De Leon Middle SchoolB
Middle · Grades 6–8 · 6.9 mi
H
Coral Gables Senior High SchoolC+
High · Grades 9–12 · 6.9 mi

District: Dade County School District

Neighborhood · ZIP 33149These are comparison scores, not percentages. 100 equals the national average, so 150 means about 50% above average.

CrimeLocal crime compared with the rest of the country, where 100 is average. It reflects things like population density, income, and how crime gets reported.72
Air pollutionOverall air pollution compared with the rest of the country, where 100 is average. Lower is cleaner.77
EarthquakeEarthquake risk and likely building damage compared with the rest of the country, where 100 is average. Scores can run far above 100.9

Index scale: 100 = US average (tick). Lower is better.

Homes occupiedThe share of homes here that someone lives in. The rest sit empty, including vacation and for-sale homes.76%
Bachelor's or higherThe share of adults 25 and older whose highest degree is a bachelor's degree.36%
Poverty rateThe share of people whose household income falls below the federal poverty line, which varies by family size.7.1%
UnemploymentThe share of men 16 and older who are out of work and actively looking. Only men are counted in this figure.0.7%
PopulationHow many people live in this area.16,714
DensityPeople per square mile. Higher numbers mean a more crowded, urban area.1,068 / mi²
Median incomeThe middle household income here — half of households earn more, half earn less.$155,699
Average incomeThe average household income. It runs higher than the median when a few high earners pull it up.$201,344
Average tempThe average temperature here across a full year.76°F
Annual precipHow much rain and melted snow falls here in a typical year.54 in
SunshineThe share of daylight hours that get direct sun in a typical year, counting cloud cover.70%

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Data by ATTOM. Valuations are automated estimates, not appraisals. Photos from Google Street View and may not depict the current property state.

How this home compares

999 Mariner Dr measured against every home in its neighborhood, its ZIP code and its county, using county assessor records refreshed nightly. A home can stand out in one of those areas and look ordinary in another, because each one holds a different mix of homes.

  • Among the most valuable homes in Key Biscayne 33149
  • Among the highest price per square foot in Miami-Dade County
  • Among the largest homes in Miami-Dade County
  • Has a bigger lot than 93% of homes in Miami-Dade County

What homes are worth in Key Biscayne 33149

Each bar is how many homes fall in that price range. The marker is this home.

This home
$501K$10M

This home is worth more than almost all homes in Key Biscayne 33149.

How it measures up in Key Biscayne 33149

The dot is this home. The mark in the middle is the typical home in Key Biscayne 33149.

Estimated value$9,999,999
CheaperTypical $1,686,851Pricier

Pricier than almost all homes nearby

Price per ft²$2407
CheaperTypical $1021Pricier

Pricier than 96% of homes nearby

Living area4,155 ft²
SmallerTypical 1,724 ft²Bigger

Bigger than 94% of homes nearby

Lot size0.36 ac
SmallerTypical 0.19 acBigger

Bigger than 82% of homes nearby

Year built1973
OlderTypical 1978Newer

Newer than 40% of homes nearby

How 999 Mariner Dr ranks against every home in each area.
MeasureThis homeKey Biscayne 33149Miami-Dade County
Estimated valuepricier than$9,999,999almost all homesalmost all homes
Price per ft²pricier than$240796% of homesalmost all homes
Living areabigger than4,155 ft²94% of homesalmost all homes
Lot sizebigger than0.36 ac82% of homes93% of homes
Year builtnewer than197340% of homes42% of homes

About 999 Mariner Dr

How much is 999 Mariner Dr, Key Biscayne, FL worth?

The TopHap Estimate for 999 Mariner Dr, Key Biscayne, FL is $9,999,999 as of Sep 24, 2026. The likely range is $9,999,999 to $9,999,999. The estimate is modelled from recorded sales, assessments and the property's own characteristics — it is not an appraisal.

When did 999 Mariner Dr, Key Biscayne, FL last sell?

999 Mariner Dr, Key Biscayne, FL last sold on Nov 5, 1999 for $1,350,000, according to the county's recorded deed.

How big is 999 Mariner Dr, Key Biscayne, FL?

999 Mariner Dr, Key Biscayne, FL has 4 bedrooms, 3 bathrooms, 4,155 square feet of living space and a 0.36-acre lot.

When was 999 Mariner Dr, Key Biscayne, FL built?

999 Mariner Dr, Key Biscayne, FL was built in 1973, making it 53 years old. The building has 1 story.

What schools serve 999 Mariner Dr, Key Biscayne, FL?

999 Mariner Dr, Key Biscayne, FL is assigned to Key Biscayne K-8 Center (elementary), rated A-; Ponce De Leon Middle School (middle), rated B; Coral Gables Senior High School (high), rated C+. All sit in Dade County School District. Attendance boundaries change — confirm with the district before relying on an assignment.

How does 999 Mariner Dr, Key Biscayne, FL compare to other homes in Key Biscayne 33149?

Among the 7,046 homes in Key Biscayne 33149, it is worth more than almost all of them ($9,999,999 against a typical $1,686,851), its price per square foot is higher than 96% of them ($2407 against a typical $1021), it is bigger than 94% of them (4,155 ft² against a typical 1,724 ft²), its lot is bigger than 82% of them (0.36 ac against a typical 0.19 ac) and it is newer than 40% of them (1973 against a typical 1978). Measured against all of Miami-Dade County, it is worth more than almost all homes there. These shares are recounted nightly from the full county assessor record for each area, not from active listings.

What are the property taxes on 999 Mariner Dr, Key Biscayne, FL?

The 2024 property tax bill for 999 Mariner Dr, Key Biscayne, FL was $34,478. The county assessed it at $2,122,820.

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