Toughest is an obstacle course race series offering distances from a 2 km Family course to a 16 km Double Distance option. Established in 2013, it provides several levels: Family for children and groups, Xplore for beginners, the 8 km main race for the full OCR format, Double Distance for a more challenging day, and Elite for athletes seeking the most difficult version. The Xplore course is 4 km, features simpler obstacles, omits the most demanding sections, and does not include timing.
The courses incorporate obstacles like Ramp, Arm Bike, Mudland, Climb, Strength, Crawl, Holmenkollen, and Dragon's Back. Holmenkollen is noted as unique globally, while Dragon's Back is the signature obstacle with international recognition. Toughest also operates an online training portal, offering videos on obstacle techniques, advice, and training plans, and provides corporate packages for team building. The series reports that 95% of participants express a desire to compete again, and participants have selected it as Europe's best obstacle course race for seven consecutive years.