What are the weird pyramids along the Skyway Bridge?

They could be the key to reducing erosion and fostering marine life.
The pyramids, called wave attenuation devices, seek to reduce coastal erosion.
The pyramids, called wave attenuation devices, seek to reduce coastal erosion. [ Florida Department of Transportation ]
Published June 7|Updated June 7

Hundreds of pyramids floating alongside Tampa’s Sunshine Skyway Bridge might first appear to be the result of a recent alien invasion or art project gone wrong.

Florida’s Department of Transportation says they actually have an important — and exciting — purpose.

The structures, which are partially submerged and pockmarked with triangular and hexagonal holes, are called wave attenuation devices. They seek to prevent continued coastal erosion alongside Interstate 275 and the Skyway fishing pier, which face a barrage of waves that splash over the seawall.

Wave attenuation devices aren’t a new concept, and similar pyramids can already be found in two different Hillsborough County locations: E.G. Simmons Conservation Park in Ruskin and Sunken Island in Hillsborough Bay.

But these concrete mammoths by the bridge (each weigh anywhere from 8,000 to 14,000 pounds and are 8 and 10 feet tall, depending on in which end of the Skyway they reside) are the agency’s most visible project yet.

Ultimately, FDOT plans to install 844 structures in two strands that are around 200 feet from the shoreline. They anticipate that the $6 million project will be done by the end of summer.

The pyramid shape, according to project manager Sergio Figueroa, helps to deflect and reduce wave energy, while the holes allow water and small marine life to pass through. Ultimately, he says, the presence of the actual structures will allow for animals to shelter within and around them — fostering biodiversity — while the reduced wave environment will promote seagrass growth and fish habitats.

Brent Setchell, district drainage design engineer, estimated that the wave attenuation devices will lead to around 8 acres of seagrass growth, which will ultimately create clearer water, more marine life and a stabilized seafloor. “We’re just really excited,” he added.

Local fishermen have also noted the potential benefits that the wave attenuation devices will have for their craft. One member of the Tampa Freedive Spearfishing Facebook group commented in a post about the pyramids that the increased marine diversity could mean “some good hunting from shore in the near future.”

Another member, who fishes near a recent installation, responded: “Stop giving away my spots.”