The annual Iditarod Trail Sled Dog Race - called "the last great race on Earth" - has become a spectator sport throughout its 1688km trek through rugged lands battling snow and ice.
The maximum number of starters is 100, each with teams of 12 to 16 husky dogs bred and trained for long-distance running.
Run since 1973, the cold classic draws big crowds to the start at Anchorage and to a lesser extent at the finish line eight to 12 days later at remote Nome - plus some TV coverage from the air.
That's still true, but now there are package air tours in which ski-equipped small planes follow the contestants and their husky-dog teams all the way.
Most thorough experience is from Alaska Tours: a 13-day adventure following the entire event from checkpoint to checkpoint aboard a ski-equipped light plane.
"While the focus is on the sled dog race, the overall experience provides a rich and detailed look at Alaska, its people and the local winter activities," the company says.
The 2011 tour begins on March 5 in Anchorage where the ceremonial start will be followed the next day by a "re-start," the race proper, at Wasilla, 72km north of Alaska's largest city.
The plane keeps pace with the race leaders and passengers have the opportunity to visit multiple checkpoints each day.
They are also given hands-on experience in "mushing" (driving) a dogteam, also fishing through the ice, snowmobiling, cross-country skiing and snow-shoeing.
Also included is a flight-seeing tour around Mount McKinley, at 6914m the highest peak in North America.
Nights are spent in comfortable lodges along the way.
"This is the ultimate tour for the Iditarod enthusiast or for the adventurer seeking a unique expedition across regions of Alaska few will ever visit," say the promoters.
The price: $US13,775 ($13,877.70) per person, including all travel meals, all excursions and a souvenir backpack and hat.
Alaska Tours also offers shorter Itadarod tours of five days, partly by air, for $US5,220 ($5258.90) per person, or four days from $US4,500 ($4533.50).
Five-days centred on Anchorage are also available from $US1,780 ($1793.30) and four-dayers from $US649 ($653.80) twin share.
Alaska Backcountry Access based in Girdwood, 64km south of Anchorage, specialises in overnight Iditarod adventures that visit various checkpoints along the route.
Travelling by snowmobile, tracked truck and commercial plane, visitors can explore the Yukon River by snowshoe, watch as the leading teams come into the Ruby checkpoint, meet local families in villages - staying in lodges.
Alaska Backcountry Access also offers tours highlighting skiing, dog-sledding, snowmobiling, gold mining, snowshoeing and guided igloo camping.
In 2011, Lance Mackay, 40, "the King of the Itidarod" will be attempting his fifth straight win that would equal the record of Rick Swenson, who won five times between 1979 and 1991.
Fastest time was recorded in 2002 by Swiss Martin Buser, clocking eight days, 22 hours, 46 minutes and two seconds.
Details: visit Alaska Tours on www.alaskatours.com.
For Alaska Backcountry Access visit www.akback.com.
In Australia call the Alaska Division of Tourism on (02) 9959-4042 or visit: www.alaskatia.org or www.travelalaska.com.