Bathtub Beach, Protected beach in Martin County, United States.

Bathtub Beach is a beach in Martin County, Florida, on the Atlantic coast of the United States, about 1,300 km south of Washington, D.C. It lies in Stuart, where average temperatures run from 18 °C in January to 27 °C in June, and rainfall reaches about 1,621 mm a year, with September the wettest month.

Bathtub Beach lies on Hutchinson Island in Martin County, Florida, where a natural limestone reef and Sabellariid worm colonies build a sandbar that shelters the shoreline. The name comes from the basin-like pool this barrier creates at low tide, warm and shallow enough to resemble bathwater. Storms repeatedly strip the sand away, and the county has rebuilt the dune and reef line after hurricanes.

The beach draws school groups and nature enthusiasts who come to explore the reef ecosystem and learn about marine life in its natural setting. Visitors can observe coastal nature firsthand and understand how the natural structures protect the shoreline.

The beach is open daily and provides parking and restroom facilities for visitors. Check the hours of operation and ask at the visitor center about current water conditions, especially during storm seasons.

The reef structure is built by tiny Sabellariid worms that cement sand grains together to form protective tubes, creating a natural breakwater system. This biological engineering is barely visible to the naked eye but plays a critical role in keeping the entire beach stable and sheltered.