Travelers should be able to climb 25 stairs consecutively, plus walk at least 1-2 miles over some uneven surfaces without difficulty. Walks typically last at least 1-2 hours at a time. Altitude can range from zero to 5,000 feet.

Travelers should be able to climb 40 stairs consecutively, plus walk at least 2-3 miles over some uneven surfaces without difficulty. Walks typically last for at least 2-3 hours at a time. Altitude can range from zero to 5,000 feet.

Travelers should be able to climb 60 stairs consecutively, plus walk at least 3 miles over some steep slopes and loose or uneven surfaces without difficulty. Walks typically last for 3 or more hours at a time. Altitude can range from 5,000 to 7,000 feet.

Travelers should be able to climb 80 stairs consecutively, plus walk at least 4 miles over some steep slopes and loose or uneven surfaces without difficulty. Walks typically last for 4 or more hours at a time. Altitude can range from 7,000 to 9,000 feet. Expect three or more one-night stays in some locations, and very limited free time for rest or independent exploration.

Travelers should be able to climb 100 or more stairs consecutively, plus walk at least 8 miles over some steep slopes and loose or uneven surfaces without difficulty. Walks typically last for 4 or more hours at a time. Altitude can range from 10,000 feet or more.