Entering its 51st year, the Horsetooth Half Marathon has become a town favourite, and for more reasons than one. Scenic Views, Challenging Course. Offering scenic point-to-point views throughout the course, the Horsetooth Half Marathon is also comprised of challenging hills along the shoreline of Horsetooth Reservoir. A great challenge for first-timers and elite runners alike, this event is unique in that although the climbs are steep, the entire course results in a net loss of elevation, making for a surprisingly fast course.