Nearly 200 concrete culverts and pipes now sit 90 feet below the Atlantic Ocean's surface, forming what developers call Jacksonville's first major artificial reef installation in several years.

The structures were dropped in late June at Harm's Ledge, a reef site about 28 miles off the Mayport Jetties, according to Jacksonville Today. The project was spearheaded by the Jacksonville Offshore Sport Fishing Club and marks a revival of the city's dormant reef-building efforts.

A New Reef Echoes Mandarin's Own Reef-Building History

In 2000 and 2001, students from Mandarin High School helped build 500 dome-shaped reef balls for the Charles H. Kirbo Memorial Reef, placed between St. Augustine and Jacksonville. Teacher Alex Waters led 22 Marine Science Research students in funneling concrete slurry into molds. The class won the 2000 SeaWorld Environmental Excellence Award and its $10,000 grant, one of eight schools nationwide to receive the honor.

Matt Blinkhorn, then a Mandarin High junior, was among 10 students who got certified to dive on the Kirbo reef site after helping build the pieces. "I know it helps the ecosystem in the water, and most of the real reefs have problems," Blinkhorn said at the time. "The more we can make and put down, the more there will be to look at."

How the Harm's Ledge Project Came Together

The new Harm's Ledge project followed a similar community-driven path. The fishing club partnered with TISIRI (Think It, Sink It, Reef It), a nonprofit that develops reef concepts using recycled materials, to design the initial plan in early 2025. They secured a grant, then coordinated with the Jacksonville Waterways Commission, Florida Fish and Wildlife Conservation Commission, U.S. Fish and Wildlife Service, Mobro Marine and others who donated the concrete materials.

Jacksonville Plays Catch-Up After a Decade of Inactivity

Jacksonville had fallen behind neighboring counties in artificial reef projects. According to March 2025 Waterways Commission subcommittee minutes, the city had not undertaken a city-led reef project in over a decade, while St. Johns and Volusia counties remained active. Jacksonville holds approved offshore reef permits dating to 2017 and valid until 2029. In May 2025, the Florida Fish and Wildlife Conservation Commission awarded Jacksonville a $120,000 grant to restart its artificial reef program.

What Comes Next for the Reef

"This reef is only the beginning," Paul Malone, the fishing club's reef development director, said in a news release. "We're building the foundation for a long-term reef development program."

The concrete pieces, loaded onto a barge with a forklift and towed to the site, will provide habitat for marine life on the ocean's sandy bottom. As coral and other organisms colonize the structures, the reef is expected to draw anglers, divers and outdoor enthusiasts.

The site is named after Gus Harms, an early fishing club pioneer. No timeline for the next deployment has been announced.