MIT Spinout's Artificial Reef Doubled a Maldives Beach in Two Years

A beach on a small island in the Maldives has doubled in size in two years after a Marriott resort installed an artificial reef designed by MIT researchers. Within the first six months, the depth of the beach along a 300-foot shoreline grew by 90 feet — without a single grain of dredged sand.

The technology comes from Coastal Assembly, a startup that spun out of MIT at the end of last year and raised $4.4 million in a funding round this summer. The company uses AI to analyze satellite and ocean current data at a shoreline, then plans the layout of custom concrete blocks that let sand accumulate naturally through the action of ocean waves.

"We take 10 years of data, and we say, where do we predict the critical areas of erosion will be in the coming months to year?" says Skylar Tibbits, a professor in MIT's architecture department who runs the university's Self-Assembly Lab. "And that tells me where the best place is to intervene—what's the part that is most critical, where we should focus our time, effort, and money."

In the Maldives project, the team installed 54 strategically placed blocks made from marine-grade concrete and local aggregate roughly 150 feet offshore. The blocks dissipate wave energy, redirecting previously lost sand back to the beach and keeping it there. The researchers track changes over time and can adjust the blocks if needed — for example, if nearby development alters wave patterns. Underwater, the reef has filled with new coral and marine life, from fish to sea anemones.

The research began by chance. Tibbits visited a sandbar in the Maldives that had emerged naturally in only a month. "It was like, wait, what do you mean, this island formed in a month? We started to understand that we could tap into this process, and then it became a question of how you promote that to happen," he says.

The incumbent solutions, in Tibbits' view, fail on both cost and durability. Dredging sand harms coral reefs and only works temporarily, as the sand can quickly wash away. "It's a continual process," he says. "One of the resorts we visited is pumping sand 365 days. . . . It's the sort of thing that everyone does as a Band-Aid."

Seawalls carry their own problems. They are expensive, and they can accelerate erosion on nearby beaches — or even at the very beach they were built to protect. As Tibbits points out, in a fight with nature, nature tends to win.

It took nearly a decade in the lab for Tibbits and his team to find an approach that worked, as they moved from simulations to 10 real-world deployments in the Maldives. AI now makes it faster to analyze the data from any given beach. Every design is custom, from the arrangement of the structures to their height and depth.

"It's not one-size-fits-all because every beach has a different bathymetry [underwater landscape]," Tibbits explains. "It has different wave conditions. There are always different complex parameters that make each beach unique."

Each structure is also cast with a unique shape so the reef looks more natural than human-made. Like natural reefs, the artificial versions help protect coastlines during storms.

Coastal Assembly is structured as a public benefit corporation, pursuing a mission alongside profit. On the mission side, it works with vulnerable communities to analyze how their coastlines are changing, and partners with the United Nations and other organizations to deploy its reefs in those areas. On the commercial side, it targets coastal resorts that want to protect their private beaches.

"Resorts are spending millions of dollars annually on coastal protection for things that don't work," Tibbits says. Revenue from commercial projects helps the company build its technology, team, and manufacturing capacity faster.

The company is now expanding in the Maldives and starting work in other locations in need of coastal protection, including Boston and Miami. Cities are recognizing that seawalls and similar structures are not the best answer. "You're seeing a big shift around the world," Tibbits says, "from hard edges to much softer, more flexible, dynamic edges." If the Maldives results replicate at scale, Coastal Assembly will have a data-backed answer to a market that currently spends millions on solutions that wash away.