Summer 2009

Weather and wave conditions can quickly turn a spectacular kayak trip into a dangerous situation. Photo: National Park Service.
UW Sea Grant Outreach

Increasing Safety at Sea Caves

By Kathleen Schmitt Kline

The Apostle Islands National Lakeshore has become a world-class destination for sea kayaking, but some of the most popular attractions can also be treacherous. At several spots around the archipelago, years of waves and ice carving through sandstone cliffs formed sea caves, a breathtaking series of delicate arches, vaulted chambers, and hidden passageways that are most easily explored by kayak.

However, under certain conditions, the sea caves can quickly change from awe-inspiring to terrifying. As waves roll into and reflect off of the cave walls, they can intensify and capsize even experienced kayakers. Once out of their boats, paddlers face the threat of hypothermia in water temperatures that hover in the mid-40s for most of the summer and rarely exceed 60 degrees. In addition, the surrounding steep cliffs make seeking safety on shore nearly impossible.

The danger is real and sobering. Over the last five years, two people have died while kayaking near the mainland sea caves about a mile east of Meyers Beach.

“Both of them were experienced athletes, and they were not unaware of the weather forecast. They just underestimated what the impact would be on them in that location,” said Bob Krumenaker, National Park Service superintendent of the Apostle Islands National Lakeshore.

Krumenaker said that conditions at Meyers Beach, where kayakers launch their boats, may seem easily manageable. However, after rounding a bend to approach the sea caves, paddlers can face significantly larger waves. Gene Clark, UW Sea Grant coastal engineering specialist, said the unique topography of the caves—combined with certain weather and wave conditions—are often to blame for the sometimes treacherous conditions.

“It’s not just one combination of conditions that can cause a dangerous situation—it’s going to be different angles, different waves, different winds, and different wave periods,” Clark said. “We want kayakers to know the current conditions so that they can decide whether or not to paddle out to the remote sea cave location.”

With support from the Wisconsin Coastal Management Program, Clark teamed up with Chin Wu, a UW-Madison civil and environmental engineer, to find out if there was some way to measure the waves near the sea caves in real-time and transfer that information back to kayakers, outfitters, and park service staff.

One appeal of exploring the sea caves is also the biggest challenge to the monitoring project—the area is very remote, with no electricity or phone lines. Clark and Wu are testing a system that includes a wave sensor on the lake bottom that monitors the size of the waves in the area. The sensor is linked by an underwater cable to a wireless, solar-powered modem mounted out of sight on the cliffs. From there, data about the real-time wave conditions can be transmitted by cell phone frequency and posted to the Internet.

Clark, Wu, and UW-Madison graduate students Josh Anderson and Kevin Lin tested some of the wave monitoring equipment this last winter, when a thick layer of ice allowed foot travel from Meyers Beach to the sea caves. They are also working with the City of Bayfield, Inland Sea Society, local outfitters, Friends of the Apostle Islands National Lakeshore, and park staff to determine the best format for presenting the real-time data from the wave sensor so that it’s most useful for kayakers.

Krumenaker stressed that the system is still in development and will be tested throughout this summer. Although it won’t be available to the public immediately, he has high hopes for the system’s eventual success.

“We expect it will save some lives,” he said.

The Aquatic Sciences Center is the administrative home of the
University of Wisconsin Sea Grant Institute & University of Wisconsin Water Resources Institute.

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