More than 12,000 cross-country skiers are expected to take part in the 33rd Engadine marathon next week (March 11). The 42-kilometre race crosses frozen lakes and winds through the Upper Engadine valley.
About 10,000 men and 2,000 women have already signed up for the marathon, but the organisers say late entries will be permitted until March 10.
There are entrants from nearly 40 countries and from such unlikely places as Hong Kong, Brazil and Israel.
Last year's winner finished the scenic course in 1:25:29. The top woman finished less than 3 minutes later. The race also attracts many elderly skiers and last year included an 89 year-old Swiss man who crossed the finish line in five hours - two hours ahead of a man 60 years his junior, who came last.
This year, less competitive entrants can choose to register as "finishers" only, which means their times won't be made public.
Refreshment stands will be set up along the course for participants and spectators alike, and alphorn musicians will play for the skiers as they race down the final stretch.
The music is likely to give the foreign entrants a competitive edge since a recent study found that alphorn music has a beneficial effect on skiers, appreciated more by foreigners than the Swiss themselves.