William Boffelli

About

William Boffelli is an Italian ski mountaineer, skyrunner, and mountain speed specialist from Roncobello in Val Brembana, now based in Courmayeur where he works as an engineer and glaciologist. A dominant force in both skyrunning and skimo, he has won the Monte Rosa SkyMarathon four times with different partners — a feat unique in that race's history. On trails he has excelled at Matterhorn Ultraks Extreme (winner, 3:25:06, 28km/3175m) and Grigne Skymarathon (winner, 4:52:50, 42km/3600m). In May 2025 he set a new Fastest Known Time on the Mont Blanc round trip from Chamonix to the summit and back in 4:43:24, beating the previous record by over 11 minutes. In 2026, alongside Mathéo Jacquemoud, he set the FKT on the Chamonix-Zermatt Haute Route (103km/8200D+ in 13:27:49).

Notable Wins

• — Mont Blanc FKT round trip 2025 (4:43:24)
• — Monte Rosa SkyMarathon (4x winner)
• — Matterhorn Ultraks Extreme (3:25:06)
• — Grigne Skymarathon (4:52:50)
• — Chamonix-Zermatt Haute Route FKT 2026 (13:27:49)