The Iditarod Trail Sled Dog Race is one of the most unique and highly controversial events on the planet. One person (musher) and a team of dogs travel between 1,000 and 1,200 miles, depending upon the year, across brutal Alaskan terrain while battling vicious conditions over an 8-15 day period.

As the race has become more competitive over the last two decades and been forced to alter its starting position and route, it has not avoided intense criticism from animal advocacy groups. Mushers and other trainers continue to face intense scrutiny for the treatment of their dogs, but the event has continued and is only getting more popular. Regardless of one’s opinion, there is no denying it is one of the most uniquely unprecedented competitions in the world.

With the 2015 race underway this week, check out some interesting photos from the race over the years: