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    Waterfront Duplex Near Sombrero Beach Title is generated by Realmo AI

    18 Man-O-War Drive, Marathon, FL 33050

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    For Sale
    $690,000

    MULTI_FAMILY - Marathon, FL

    Property size:
    834 SF
    Lot size:
    0.12 Acres
    Price / SF:
    $827/SF
    Added:
    Feb 4, 2026
    Days on Market:
    107
    Last Refresh:
    May 22 at 7:06 pm

    Property Features for 18 Man-O-War Drive

    General Information

    Property type
    Residential Multi Family
    Property subtype
    Other
    Zoning
    RM - Residential Medium
    Bedrooms
    2
    Bathrooms
    2
    Rooms
    Bedroom 2, Bathroom 1, Bathroom 2, Bedroom 1
    Parking features
    Open
    Pets allowed
    Yes
    Appliances
    Washer, Dryer, Dishwasher, Refrigerator, Oven, Microwave, Stainless Steel Appliance(s)
    Standard status
    Active
    APN
    00354810-000000
    Size
    834 SF
    Lot size
    0.12 Acres

    Taxes and HOA fees

    Tax Year
    2025
    Tax Description
    BK 1 WLY PORTION OF LT 11 SOMBRERO BEACH VILLAGE PB5-86 BOOT KEY OR426-148 OR789-1794/95 OR851-2341 OR1019-1371/73 OR1
    Tax Annual Amount
    5806

    Utilities

    Heating system
    Central
    Cooling system
    Central Air
    Water front
    1

    Building Details

    Year built
    1971
    Floors in Building
    1
    Flooring type
    Vinyl
    Building materials
    CBS
    Roof type
    Metal

    We can help!

    Listing Contact
    Cara Ann O'Neill

    Listing agent Cara Ann O'Neill License #3631899

    Listing office Key Colony Beach Realty 220 Key Colony Beach Causeway P.o Box 510095, Key Colony Beach, FL

    Listing date Feb 4, 2026

    MLS# 618482 Listing URL

    Copyright © 2026 Marathon and Lower Keys Association of Realtors. All rights reserved. All information provided by the listing agent/broker is deemed reliable but is not guaranteed and should be independently verified.

    HighLights

    • Waterfront property with new 45‑ft dock and new seawall, ideal for boating.
    • Short walking distance to Sombrero Beach.
    • Newly updated with new vinyl plank flooring, updated kitchen with stainless steel appliances, and fresh paint.
    • Strong rental income opportunity or low‑maintenance permanent home.
    • Priced below appraised value.
    • Opportunity to purchase the entire duplex (adjacent unit also available).

    Overview

    This newly updated waterfront half-duplex is located within walking distance of Sombrero Beach. The canal front property features new vinyl plank flooring throughout, along with an updated kitchen equipped with stainless steel appliances. Freshly painted inside and out, the home offers a modern feel and is move-in ready. The property includes a new seawall and a new 45-ft dock. It also provides partial open-water views, suitable for boating and waterfront living. The property size is 834 square feet and the lot size is 0.12 acres. This property is zoned RM - Residential Medium. It can be used as a rental income opportunity or a low-maintenance permanent waterfront home. The other half of the duplex is also available for purchase, offering the chance to own the entire waterfront property.
    Property Profile Location Intelligence

    Current Use by Public Records

    Duplexes

    Map

    City
    Marathon
    County
    Monroe
    State
    Florida
    Longitude
    -81.079503
    Latitude
    24.70126

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    FAQs

    What type of property is this?
    Duplex - Updated waterfront duplex, move-in ready, near Sombrero Beach.
    Where is this duplex located?
    The property is located at 18 Man-O-War Drive Marathon, FL.
    What is the asking price?
    The asking price for this property is $690,000.
    What are key features of this property?
    This property features: Waterfront property with **new 45‑ft dock and new seawall**, ideal for boating.; Short walking distance to Sombrero Beach.; **Newly updated** with new vinyl plank flooring, updated kitchen with stainless steel appliances, and fresh paint.
    (305) 731-7887
    We can help!
    Listing Contact
    Cara Ann O'Neill
    Real Estate License ID: 3631899
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    Realmo Value Estimations

    Realmo estimates a property’s market value using a proprietary methodology that incorporates public data and user-submitted information. This cumulative value is generated by integrating a variety of conventional and innovative methods. 

    Disclaimer

    These figures are not official appraisals and should not be used as a substitute for a valuation performed by a licensed appraiser.
    Actual market value may differ due to factors not captured in the data. Estimates are offered for informational purposes only, and users should conduct independent research before making financial or investment decisions.
    By using this feature, you acknowledge that Realmo is not responsible for actions taken based on these estimates.

    AI approach

    Realmo AI Method estimates property value using machine learning models trained on millions of comparable listings, transactions, and market signals. It analyzes property features, location intelligence data, and current market dynamics to predict the most probable market value in real time.

    Realmo CapRate Calculation

    Realmo calculates the Capitalization Rate (Cap Rate) to help estimate a property's potential return on investment. The Cap Rate is a fundamental metric in commercial real estate that measures the relationship between a property's net operating income and its market value.

    How We Calculate Cap Rate

    Cap Rate Formula:
    Cap Rate (%) = (Net Operating Income / Property Value) × 100

    Net Operating Income (NOI) Formula:
    NOI = Area × Lease Rate × (1 - Vacancy Rate) × (1 - Operating Expense Ratio)

    Components

    Net Operating Income (NOI) represents the annual income a property generates after operating expenses:

    • Area: Building square footage from property records
    • Lease Rate: Annual $/sqft based on market data for the property type and geographic location
    • Vacancy Rate: Percentage of unoccupied space based on market data for the property type and location
    • Operating Expense Ratio: Operating costs as a percentage of income, varies by property type

    Property Value is derived from:

    • Recent sale price (if available)
    • Statistical models using comparable sales
    • AI-powered valuation estimates

    Example Calculation

    For a 100,000 sqft Office Building:

    • Lease Rate: $25.00/sqft/year (market data for Office in this area)
    • Vacancy Rate: 8% (market data for Office in this area)
    • Operating Expense Ratio: 35% (typical for Office properties)
    • Property Value: $15,000,000

    Step 1: Calculate NOI

    NOI = 100,000 × $25.00 × (1 - 0.08) × (1 - 0.35)
    NOI = 100,000 × $25.00 × 0.92 × 0.65
    NOI = $1,495,000/year

    Step 2: Calculate Cap Rate

    Cap Rate = ($1,495,000 / $15,000,000) × 100
    Cap Rate = 9.97%

    Property Type Considerations

    Net Operating Income calculations vary by property type due to different operating expense ratios:

    • Office: Higher expenses (30-40%) for HVAC, utilities, maintenance
    • Retail: Moderate expenses (25-35%) for common area maintenance
    • Industrial/Warehouse: Lower expenses (15-25%) for minimal tenant services
    • Multifamily: Moderate expenses (35-45%) including property management
    • Self-Storage: Lower expenses (25-35%) due to minimal maintenance

    Market lease rates and vacancy rates are specific to each property type and geographic location, reflecting local market conditions.

    Disclaimer

    These calculations are estimates for informational purposes only and should not be used as a substitute for professional financial analysis or appraisal.

    • Cap Rate calculations depend on market data that may change over time
    • Actual operating expenses, lease rates, and vacancy rates may differ from market averages
    • Individual property conditions, lease terms, and tenant quality significantly impact actual NOI
    • Property value estimates are approximations and not official appraisals
    • Cap rates vary widely by market, property condition, and investment risk profile

    Professional Guidance Recommended: Before making any investment or financial decisions, consult with licensed appraisers, commercial real estate brokers, and financial advisors who can evaluate your specific property and circumstances.
    By using this feature, you acknowledge that Realmo is not responsible for investment decisions or actions taken based on these estimates.

    Cap approach

    Capitalization Method calculates value based on estimated net operating income (NOI) and applying a market-based capitalization rate (cap rate), we estimate what a typical investor might be willing to pay for it.

    Comparable approach

    Comparable estimate is based on recent sales of similar nearby properties, adjusted for factors like size, condition, and location.

    Relative

    Relative property class coefficient uses factors that account for typical price differences between various asset types (e.g., retail vs. industrial) to provide a more accurate market-aligned estimate.

    Geo

    Comparable Sales Method, enhanced by Geo coefficients — location-based adjustment factors that reflect differences in price levels across neighborhoods, cities, or regions ensuring a more accurate, market-sensitive valuation.

    Stat Estimate

    This method estimates value based on actual market adjusted recent (~5 years) sales of comparable properties around by location and property type.

    • Ranges - area data calculated by industry standard IQR Outlier Removal Method
    • Range-from: 75% of all similar sales ($/sqft) are above this value
    • Range-to: 75% of all similar sales ($/sqft) are below this value
    AI Estimate

    This method estimates value based on AI market estimation of comparable properties around by location and property type.

    • Ranges - area data calculated by industry standard IQR Outlier Removal Method
    • Range-from: 75% of all estimations ($/sqft) are above this value
    • Range-to: 75% of all estimations ($/sqft) are below this value
    Alternative use

    Estimate considers the property’s potential value if used for a different purpose-based on zoning, demand, and market feasibility.

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