Monster of Mazinaw Trail Race

Cloyne, Canada • 20 Sep 2025

Monster of Mazinaw Trail Race 2025 unfolds at Bon Echo Provincial Park, Ontario (Cloyne). The event features three trail distances: 10k, 30k, and 43k—the last billed as Canada’s shortest ultramarathon, but the rugged course feels longer. The route blends wide groomed trails with technical rocky single-track, including long, self-reliant back-country sections where aid is sparse and runners must carry essentials.

Expect rocky roots, steep climbs and descents, and potentially slippery conditions; the 30k has yielded about 575m of gain. Aid stations offer water, electrolyte drinks, PB&J and snacks; the event is cup-less. Athletics Ontario sanctions the race; it is capped at 275 participants, with La Sportiva demos and shoe giveaways. Visit the organization's website for the most recent information.

Race information

43 km
43k Trail Race
30 km
575 m+
30k Trail Race
10 km
10k Trail Race (approximately 11k)
Visit the organization's website for the most recent information.
Trail runs nearby