Surfing fin–embedded sensors collect coastal data.

Kat Hammond

Scientists put a ‘smartfin’ on my surfboard. Is it the next wave in ocean monitoring?

At 10:24:05 a.m. on 29 August, I entered the Pacific Ocean, surfboard in hand, at Swami’s, a break near my home in Cardiff, California. I paddled out and, for 93 glorious minutes, surfed the best waves I’d ridden all month. During my session, the water temperature fluctuated between 20.33°C and 21.38°C.

I know all of this, to several decimal points, thanks to the work of two scientists I surfed with that day, engineer Phil Bresnahan and coastal biogeochemist Tyler Cyronak, both of the Scripps Institution of Oceanography in nearby San Diego. With support from a New York City–based nonprofit called the Lost Bird Project, Bresnahan and Cyronak have developed a surfboard fin that contains a temperature sensor, a GPS device, a circuit board with a microcontroller, a Bluetooth chip, and a rechargeable battery; eventually, they plan to add sensors for pH, chlorophyll, salinity, and oxygen. The technology is packed into a milled-out section of the 13-centimeter-tall “smartfin,” one of which they loaned me to test surf.

The goal isn’t to help surfers monitor their surf sessions. Instead, they are aiming to gather data for studies of the coastal zone. They hope to distribute the fins widely enough to provide valuable data for researchers who track the health of sea life–rich reefs and kelp forests or monitor coral bleaching, the mixing of atmospheric gases by breaking waves, riptides, pollutants, and, over time, the ocean’s absorption of heat from global warming. 

In collaboration with the Surfrider Foundation, an environmental nonprofit started by surfers, Bresnahan and Cyronak have loaned 50 smartfins over the past 3 months, and data are beginning to pour in. Cyronak notes that the California coast has temperature gauges on some piers, but they are few and far between. “Scientists want coastal data and the coast is hard to monitor,” he says. “To really understand what’s happening in the coastal zone you need a lot of measurements.”

Jon Cohen (left), Tyler Cyronak (middle), and Phil Bresnahan (right) after a surf session with the smartfin near San Diego, California.

Swami's Johnny

To Robert Brewin, a satellite oceanographer at the Plymouth Marine Laboratory in the United Kingdom, there’s a “huge potential to use surfers as a platform to improve sampling” of the near-shore environment. His own lab has done just that—using different technology—for the past 3 years. Brewin, who specializes in modeling phytoplankton populations and surfs the chilly waters off Plymouth, clipped temperature sensors to the leashes that attach a surfer’s ankle to the board. A fanny pack held a GPS device tucked inside a waterproof bag. His team of surfing scientists has made more than 400 observations to date.

As his group described in recent papers published in PLOS One and Estuarine, Coastal and Shelf Science, the surfer-collected sea surface temperatures show that satellite measurements become unreliable near shore. Temperature data from satellites outfitted with an infrared scanner called an Advanced Very High Resolution Radiometer (AVHRR) closely match measurements from buoys, which are outfitted with sophisticated sensors, located about 7 and 33 kilometers from shore. But the AVHRR data on near-shore temperatures appeared significantly less reliable. “We can’t trust the satellites or the models in that environment as they haven’t been evaluated,” Brewin says.

The smartfin’s GPS and temperature sensors recorded changes over the entire surf session, including hints about when the board was riding a wave (spikes in acceleration recorded by blue dots).

A bespoke creation

He sees the smartfin as a “bespoke tool” that’s a vast improvement over his bulky and less precise system. “One of the slight difficulties with the kit we’ve been using is it isn’t well suited for the widespread citizen science use,” notes Brewin, who is now testing five smartfins. “The fin really has potential to engage citizens.” He calculates that in the United Kingdom alone—which, no disrespect, isn’t exactly known for its surfing—there are enough surfers to make 40 million environmental measurements per year.

Andy Stern, a retired neurologist based in Rochester, New York, who runs the Lost Bird Project and hatched the idea of the smartfin 4 years ago, says there are no plans to distribute the fins on a massive scale. “Success does not mean how many fins are out there,” says Stern, who notes that the smartfin is funded by donations and does not intend to sell the product. “I have racked my brains about a business plan about how to make this fly.” Now, making a smartfin and its battery charger costs about $300, he says. “It will never be in a surf shop next to other fins for sale.”

Smartfin is seeking a grant from the National Science Foundation, says Stern, who hopes the device will “fill a data gap” in coastal research and spark the development of new miniaturized sensors. He adds that the smartfin is “a symbol to help inspire and empower local communities toward climate mitigation and science-based policy.”

From feathers to fins

The notion of the smartfin as a climate change conversation spark meshes with its parent project Lost Bird, which has placed sculptures of great auks, Labrador ducks, Carolina parakeets, heath hens, and passenger pigeons in the North American locales where they were last seen before going extinct. These “avian memorials” hope to make people realize the impact they have on the environment—or as Lost Bird’s motto puts it, “connecting more deeply with the earth through art.”

Bresnahan says the smartfin has “a messaging appeal to a broader audience” than just surfers. “When I went home for Christmas this year and told people I was working on a surfboard project for ocean health, everyone circled around me and wanted to learn more.”

I know they didn’t design the smartfin so I could track my surfing, but I asked Bresnahan and Cyronak whether the GPS revealed how many waves I rode during our session. “I’m a little uncomfortable making confident claims here,” Bresnahan emailed me. “My count for you is ~ 21, but we really don’t have a good way to determine that yet.”

The number of waves a surfer rides during a session is of course perfectly meaningless, but I am astonished that the data are there to plumb and even debate. And that, in the end, may be the value of the smartfin. “People always ask us what the data are going to be used for,” Bresnahan says. “We think there’s a need for new sensors and platforms, and until we’ve had them out there for a while, we won’t even know the questions.”