The Toughest Thirteen

43-year-old John Curley of Ireland en route to completing The Toughest Thirteen after completing the 16 km Round-Trip Angel Island with Clare O'Connor piloting in August 2025

noun - The Toughest Thirteen (T13 or MSF Toughest Thirteen) is a group of 13 extremely challenging open water swims for the advanced solo marathon swimmer as defined by the Marathon Swimmers Federation and created by Evan Morrison.

History

The T13 was created by Evan Morrison in 2019 as an alternative to the Oceans Seven, focusing on extremely challenging and less known swim routes.

ʻAlenuihāhā Channel: 47 km (minimum) swim between the islands of Hawaii and Maui in the state of Hawaii
Beltquerung: 25 km swim across the Fehmarn Belt in the Baltic Sea between Denmark and Germany
Dál Riata Channel: 21 km swim from Mull of Kintyre in Scotland to Ballycastle in Northern Ireland
Big Swim Derwent River Marathon: 34 km swim in the Derwent River in Tasmania, Australia
False Bay: 33 km between Rooi Els to Miller's Point in South Africa
Fastnet Rock: 15.6 km (minimum) swim from County Cork on the Irish mainland
Foveaux Strait: 29 km swim between Stewart Island/Rakiura and from New Zealand's South Island
Gulf of the Farallones: 33 - 48 km between the Farallon Islands and California mainland or the Golden Gate Bridge in California, USA
Loch Ness: 36 km across the famed lake in Scotland
Monterey Bay: 37 km swim across the bay along central coast of California, USA
Round-Trip Angel Island: 16 km swim between Aquatic Park and Angel Island in San Francisco Bay in California, USA
Strait of Juan de Fuca: 17 km swim between Vancouver Island in British Columbia, Canada and the state of Washington, USA
Lago Titicaca: 15 km (minimum) swim in world's highest commercially navigable lake located on the border of Peru and Bolivia