Ultra Łoś is a trail race held in October within the Łosiowe Góry Landscape Park, close to Grudziądz, Poland. It features four routes across hilly, predominantly unpaved terrain. The distances are: 25 km (Klępa route) with 350 m elevation gain, 42 km with 600 m, 62.5 km with 650 m, and an 85 km Hardcore route covering 1,400 m ascent and 1,400 m descent. All participants begin simultaneously, sharing the initial section before the distances diverge.
The 85 km race serves as the primary challenge, requiring completion within 14 hours. It includes four aid stations and carries an ITRA Mountain Level Finisher rating of 410. Now in its fifth edition, this longest distance attracts the most participants, around 200 runners, whereas the shorter routes have fewer competitors. The Klępa 25 km is suitable for those progressing towards longer mountain ultras, though its finishing times indicate it's also utilized by swift trail runners for a demanding shorter race.