Visit extremeworldraces.com to learn about the Siberian Black Ice Race, a 379 mile marathon (although a shorter 155 mile course is available) in which adventurers ski, hike, and snowkite across frozen northern Russia.  The marathon event runs from March 15th through April 10th, 2012. Tony Martin, the CEO of Extreme World Races, describes the race as "Longer than England, colder than vodka and harder than granite."  Check it out.