Nantucket to Martha's Vineyard Jaws 18-Mile Open Ocean Relay Swim

In 1948, the residents of Edgartown faced a logistical puzzle: they needed a reliable connection to Chappaquiddick, and they needed it immediately. They built a ferry in less than two weeks, aptly naming it 'On Time'—a vessel that would define the local pace of life for decades. Today, swimmers tackling the 28.9km relay from Nantucket’s Eel Point to the Edgartown Lighthouse channel that same sense of urgency and endurance. Organizing a crossing of this scale requires substantial resources, including dedicated escort power boats, local captains, and expert kayakers to navigate the complex hydrology of the sound, which explains the $950 entry fee.

The currents and the coast

As you navigate the open water, the environmental history of the region becomes physically apparent. A 2007 breach in the barrier beach shifted the local tidal dynamics, creating a persistent three-knot current that flows through Katama Bay and the harbor entrance. This force demands precise navigation, especially when passing areas like Muskeget Island, the southernmost breeding ground for grey seals. These colonies are a magnet for local marine predators, turning the swim into a genuine test of ocean awareness. Further along the approach to Martha's Vineyard, you will pass the historic 19th-century mansions of whaling captains. Many of these homes feature the distinctive 'widow's walk' atop their roofs, a architectural necessity historically used to dump sand on chimney fires rather than for gazing out at the horizon.

Strict channel traditions

This event is governed by traditional English Channel rules: no wetsuits, just standard swimsuits, goggles, and swim caps. The relay format involves one-hour rotations, reflecting the rigorous standards set by marathon swimming culture. While the 1969 Chappaquiddick incident—where a vehicle went off a bridge into the nearby Poucha Pond—remains a somber marker in local history, the focus for today’s athletes is strictly on the water between the islands. The swim concludes at the Edgartown lighthouse, where the coastal heathland of the surrounding area—an endangered plant community found only in the Northeast—provides a stark, natural finish line after eighteen miles of open-ocean exposure.