Travel Reference
In-Depth Information
In Praise of High Mountain Passes
A Yellowstone experience that's always a delight in good weather is the opportunity to
sample a high pass in the Rocky Mountains. At three places in the park, the main road
climbs above 8,000 feet (2,440 m). Besides Sylvan Pass, the other high passes are Craig Pass
between Old Faithful Village and West Thumb Junction (8,262 ft / 2,518 m), and Dunraven
Pass, the highest (8,873 ft / 2,704 m), between Tower Fall and Canyon Junction.
What's Different about Mountain Passes?
You can tell you're in a special environment even without getting out of your car. In June
and early July, there are still mounds of snow along the road. Waterfalls spill onto the road
and fall down to the river.
You'll see a profusion of wildflowers in July and August. They have only a few weeks to
show their splendors and produce their seeds.
Trees that grow this high on the mountainsides belong to species that have adapted to
the climate, predominantly subalpine fir and whitebark pine. In very high windy places,
they may show crooked growth called
krummholz,
German for “crooked wood,” with
branches only on the side away from the wind.
Sometimes there are gorgeous vistas at or near the mountain passes. In the case of
Sylvan Pass, the best views are a few miles to the west of the pass itself.
Some park animals spend the summer months this high or higher. Bears gorge them-
selves at the end of summer on berries and whitebark pine nuts. Especially around Dun-
raven Pass, you may see bighorn sheep if you look up to the crags above the road.
How Do You Feel?
At altitudes of over 8,000 feet (2,400 m), almost everyone feels some effects from the thin-
ner air. You may feel dizzy, faint, or seem to have trouble getting your breath. The atmo-
spheric pressure is 27 percent less than at sea level, thus the air around you is less dense,
and you're only getting about three-quarters as much oxygen per breath. However, if you
stay at high altitude for a few days, your body will usually accommodate at least partially
to the reduced oxygen supply. Another high-altitude effect is increased UV radiation, even
on cloudy days.
You can park in the picnic area at the west side of the lake for
Avalanche Peak Trail.
This trail takes you in a very steep 2 miles (3.2 km) to the top of Avalanche Peak. Rangers
sometimes lead hikes up this trail; inquire at Fishing Bridge Visitor Center.
