The Marathon Swimmers Federation (MSF) has announced that Karen Zemlin is the recipient of the 2025 Yudovin Award for Most Adventurous Swim. The prestigious international honor recognizes Zemlin’s groundbreaking 14.2-mile (22.9 km) crossing of Lake Superior, a journey from Isle Royale, Michigan, to the remote tip of Minnesota at Pigeon Point at the age of 57.

Completed on August 13, 2025, the swim was selected by the global marathon swimming community for its spirit of discovery and the extreme environmental challenges Zemlin overcame. While the crossing began in manageable 64°F waters, Zemlin encountered a massive "upwelling" during the second half of the swim. Within the final miles, water temperatures plummeted to a bone-chilling 46.9°F—an almost 20-degree drop that is the coldest temperature ever recorded for a MSF documented swim. Following MSF rules, the swim was done without a wetsuit.

Superior Swims: A New Resource for Adventurers

As a lifelong Minnesotan, Zemlin’s historic crossing serves as a hallmark for SuperiorSwims.org, a newly launched digital hub for ultra-marathon swimming on Lake Superior. The site serves as a "living resource" for athletes drawn to the beauty and scale of Lake Superior, providing route data, pilot resources, and safety information. As the founder of the site, Zemlin hopes her Isle Royale-to-Pigeon Point route will inspire international athletes to explore the wilder, less-documented corridors of the lake.

A Legacy of Endurance

The Yudovin Award, named in honor of prolific pioneer David Yudovin, is given to swimmers who choose the "road less traveled." Zemlin’s career has long been defined by this ethos. Her resume includes:

The Triple Crown of Open Water Swimming: English Channel (age 51), Catalina Channel (age 50), and Manhattan Island (age 46)

END-WET Red River: Fastest times for a female in both the 43.5k (age 45) and 57.9k (age 54) courses.

Lake Mille Lacs: The first person to complete a documented crossing (age 51).

Lake Minnetonka Challenge (USMS Nationals): First place female in the 16.1k race (age 44)..

Madeline Island: Only person to solo the 32.2k course around the island (age 46).

Zemlin’s passion for the water was fostered by her father, the late Roger Bosveld, a legendary Minnesota swim coach. She often credits her high school coach at Mounds View, Jim Brobin, whose mantra—“It’s what you do after you’re tired that counts”—has guided her through decades of ultra-distance challenges.

About the Marathon Swimmers Federation (MSF: ultraswimming.org)

The MSF is the global governing body for unassisted marathon swimming. The annual awards recognize the year’s most significant achievements in solo swimming, relays, and adventurous spirit, as voted on by peers in the international community. ultraswimming.org

Superior Swims is the premier resource for open water and marathon swimming on Lake Superior. It provides a community platform for athletes to chart courses through the "beauty, cold, and sheer scale" of the inland sea. superiorswims.org

More information on Karen Zemlin: https://www.openwaterpedia.com/wiki/Karen_Zemlin