Is the Tough Guy really the toughest race? Maybe over two or three hours, but here are five ultras that will make you think twice.

Alaska Ultra Sport
Just like the Iditarod, but 350 miles on foot or 1,100 miles by bike. Key stat: Minus 35 degrees F. Next race: February 28, 2010.

Badwater Ultramarathon
The mack daddy: 135 miles from the lowest point in the contiguous States (Badwater, Death Valley) to the highest (Mt. Whitney). Key stats: 13,000 feet of climbing, 4,700 feet of descending, temps up to 130 degrees F. Next race: July 12-14, 2010.

The Barkley 100-Mile Run
How tough can it be to run 100 miles? Well, since 1986 only eight of 700 runners have finished under the 60-hour cutoff time. Key stats: 52,900 feet of climbing, 52,900 of descending. That’s not a typo. Next race: Who knows–it’s rather underground. Unofficial FAQ here.

Race Across America
One of the originals: Just you on a bike, crossing the country. Key stats: RAAM is 50 percent longer than the Tour de France and solo racers finish in about half the time. Next race: June 8, 2010.

Race Across Oregon
At 538 miles, this bike ride is longer and tougher than California’s Furnace Creek 508. Key stat: The RAO starts with a 35-mile, 4,700-foot climb. Next race: July 24-25, 2010.

Tour Divide, a.k.a. Great Divide Mountain Bike Race
The longest off-pavement bike race, GDMBR logs 2,745 miles from Canada to Mexico and grapples with 200,000 feet of climbing. Key stats: 0 support allowed, 0 communication allowed. Next race: June 11, 2010.