The Hillary, New Zealand

Who: 200 runners

When: March 14, 2015

Why it's unique: The Hillary Trail Run is a three- to four-day trek that opened in January 2010 on Aukland's west coast and is named for explorer, Sir Edmund Hillary. And true to form, there is no marathon along this track – just a 50-mile ultra that climbs a staggering 12,000-feet and requires you to carry a first-aid kit specifically outfitted to assuage your knees for the pounding they're promised to be dealt on the downhill. [thehillary.co.nz]