Harbor Isle is a charming, established residential neighborhood in Marathon, Florida, situated in the heart of the Florida Keys at approximately mile marker 48.5 to 50 along the Overseas Highway. This community features a mix of single-family homes, many with canal-front or waterfront access, offering residents a quintessential Keys lifestyle centered around boating, fishing, and relaxed island living. Developed in the mid-20th century, the area maintains a low-key, residential vibe with mature landscaping and a sense of history as one of Marathon's older subdivisions.

The neighborhood is characterized by its proximity to the water, with numerous properties providing direct or easy access to canals leading to the Gulf or Atlantic. This makes it particularly appealing for boat owners and water enthusiasts. Homes range from modest single-story residences to more updated properties, many emphasizing outdoor living spaces suited to the tropical climate.

Lifestyle in Harbor Isle emphasizes independence and connection to the natural surroundings. Residents enjoy the freedom of no community association oversight, allowing for personalized property use, including flexible rental options where local regulations permit. The area benefits from Marathon's overall amenities, including nearby parks, beaches, and marine facilities, while maintaining a peaceful, neighborhood feel away from heavy tourist traffic.

Notable aspects include its location in the vibrant Middle Keys, providing convenient access to local dining, shopping, and recreational activities. The community supports a mix of year-round residents and seasonal visitors drawn to the Florida Keys' unique environment of crystal-clear waters, abundant marine life, and outdoor adventures. Harbor Isle represents an authentic slice of Keys living without the structured rules of newer master-planned developments.