Amphitheater Mountain has an amphitheater for its west side. So there's the reason for the name. Some [cough...Fred Beckey...cough] like to name it in the English way (Amphitheatre) but, for the time being anyway, it's "er" on the map so "er" it is here on summitpost.
So where is this amphitheater and can I take in a concert there? Yes, yes you can: but the creatures making music will not be rock stars with long hair--unless you consider a pika a rock star with long hair. Your concert with be the timeless wilderness melody of birds and marmots with perhaps the odd accompanying bass butt burp from your hiking companion.
Amphitheater Mountain is the triple-summited, T-shaped massif roughly one-mile south of higher Cathedral Peak. Cathedral and Amphitheater are members of the Washington Top 100. As such, for those working on completing this list, Cathedral and Amphitheater are done on the same trip. They can both be done on the same day--and even on approach day if you approach via Canada. A convenient gully allows direct access from Cathedral to Amphitheater and visa versa. This gully cannot be seen until east of Upper Cathedral Lake.
The south summit of Amphitheater is the highest point (8,358 ft). It features a short mantle onto a block. Other than that, the terrain is easy walking. The west summit (8,252 ft) and north summit (8,200+ ft) are also easy, though the latter involves a bit of scrambling. Each summit commands a great view, though for different compass points. The north summit is best for viewing Cathedral Peak and, if you walked the craggy ridge northeastward to its termination, a view of Cathedral's fantastic Southeast Face.
The long north wall of Amphitheater stretches for three-quarters-of-a-mile on either side of Cathedral Pass and has only one easy break in it (the aforementioned access gully). The wall averages 500 feet in height and contains many as yet undiscovered multi-pitch rock climbs (if you can deal with the lichenous rock). You could spend several days just creating new lines along the wall. Further, there is an east wall above Cathedral Creek that warrants attention.
The approaches for this mountain are the same as for Cathedral Peak. They are reprinted below. Cathedral and Amphitheater are generally done on the same trip as they are only a mile apart. The easiest route up Amphitheater is via its western "amphitheater" so the Andrews Creek or the Chewuch River approaches would be most apropos. But, by use of the hidden access gully on Amphitheater's north slope, you can also approach via the Tungsten Creek trail or from Canada.
Andews Creek Trail
Drive 23.5 miles north out of Winthrop on the Chewuch River Road. The trail starts at 3,050 ft. Andrews Creek Campground is here. Hike the trail for 12 miles to 6,680+ ft Andrews Pass. Only five more miles to go to reach the peak! Descend the trail on the other side of the pass in the Spanish Creek drainage. In 2 miles (c. 6,300 ft) reach a junction with the Spanish Creek Trail on the left. Stay straight. In another mile reach the wilderness guard station (c. 6,750 ft). Say hello to the ranger there, if there. Just before the cabin on the right is the trail up to Cathedral Lakes. This trail can be taken for 3 miles to Upper Cathedral Lakes at the north foot of Amphitheater's west summit. Total distance from trailhead to Upper Cathedral Lake is approximately 17 miles. The overall gain is about 4,800 vertical feet. Subtract one mile if heading only to Amphitheater's west side.
Chewuch River Trail
Find yourself in the town of Winthrop (SR-20). Drive one of two roads (either West Chewuch or East Chewuch Road) north out of town. These two roads converge in about five miles. Continue north up Chewuch (aka Chewack--the name that appeared on maps in 1859) River Road. In 29 miles from Winthrop (5.5 miles beyond the Andrews Creek Trail) you will reach the end of the road and the trailhead (elevation 3,420 ft) on the west side of the river. A footbridge goes across the river where the trail continues northward up the other side. There is a cut-off trail that shortens the approach but is only really worth it if you'll be driving from the west (from the Okanogan River Valley). See the Windy Creek Cut-Off description on the Remmel page for more information.
Hike the flat river trail for 8 miles to the junction (4,650 ft) with the Tungsten Creek Trail. There are two options here: continue on the Chewuch River Trail or take the Tungsten trail. The latter is better if your intention is to aslo climb Cathedral Peak's Southeast Face because the trail goes right past it. In fact, this is the only approach that will give you a view of that face unless you purposely go over there to have a look after you approach the peak from the west or northwest.
In 6 miles from the junction (14 miles from the car) reach the Cathedral Creek-Remmel Creek confluence. The trail continues westward up Remmel Creek toward Remmel Lake 1.5 miles SSW of Amphitheater. In 1.8 miles (15.8 miles from the car), a trail goes right (north) and eventually reaches Upper Cathedral Lake in 3.5 miles. Total distance via this option is approximately 19 miles with an elevation gain of around 4,500 vertical feet.
For the Tungsten approach, go north up Tungsten Creek. Reach the junction with the Boundary Trail at the Tungsten Mine (6,800 ft) in 6 miles (14 miles from the car). Go west on the Boundary Trail as it loops around and up to Apex Pass (7,300 ft) and your first views of Amphitheater Mountain. Continue on the for three miles to 7,600-ft Cathedral Pass Upper Cathedral Lake is just west of the pass. Total distance via this option is approximately 20 miles with around 4,700 ft of gain.
Wall Creek Trail & Approach
This is an approach from Canada. I will make no comments as to the legality of crossing the International Border here. Be warned that the Border Patrol is active in the Pasayten. Their main quarry are drug runners but I'm sure they'd hassle you too. Besides, you're supposed to have a permit if you're in the Pasayten Wilderness. There are no permit stations for you north of the border. But don't let the patrol worry you too much. It is a large area this wilderness.
Drive Canada's Highway 3 between Princeton and Keremeos. The Ashnola River Road junctions off of the highway at 40 miles east of Princeton and 2 miles west of Keremeos. The road is not clearly marked. Distance signs on the road once you get in the valley proper are in kilometers. These are the yellow signs with black numerals attached to trees on the east side of the road.
At the 38km point (3,800 ft) there is a small pull-out on the left with a footbridge across the river. This is the Wall Creek Trail but it is not marked. Hike the trail for about 2 miles to 5,000 ft. When the trail starts going up to the left toward Wall Creek Meadows you want to leave it for it doesn't lead you toward Amphitheater Mountain.
Drop southward from the Wall Creek Trail and cross the creek and continue a short distance but no more than a quarter mile up the winfall clogged Cathedral Fork. You DO NOT want to continue up the bottom of the valley. Move right (west) and make a diagonal ascent southward in easy forest to the north end of Border Ridge, whose highest point (7,404 ft) is in the United States. Gain the ridge crest or its immediate east side and follow it to the International Border (roughly 3.5 miles from the trail). Cross the weird swath cut through the forest. The ridge turns southwest, goes over the highest point, then turns south again. In about one mile south of the highest point the trail to Lower Cathedral Lake will be crossed at c. 7,080 ft. As I recall this trail was not all that obvious. You can take this trail to the upper lake where there is good camping but it is not the most direct to Amphitheater's west side. Instead, continue southeast off Border Ridge to the low divide (7,000 ft). Cross lovely parkland ESE and contour around the south shoulder of Pt. 7685 west of Amphitheater. Pick up the Boundary Trail and take it too the area at Amphitheater's west base. Total distance is approximately 10 miles with 4,500 ft of gain.
A Trail Park Pass is required at the Chewuch River Trailhead and the Andrews Creek Trailhead. At these trailheads you are asked to fill-out a wilderness permit. You could ride a bike up the Chewuch River Trail at least to the wilderness boundary sign, which was passed at someplace in the first few miles. It would be possible to ride all the way to Mile 36 on the map. The trail is not steep up to that point. The only red tape for the Canadian approach is the invisible red tape that is stretched endlessly along the International Border.
When To Climb
The best time is summer if only for the fact that access is an issue at other times of year. Early summer would be ideal for the enjoyment of wildflowers and green grass. But lingering snow could hide these, so let's say July is the best timeframe.
Camping is available in several places along the approach routes. Care must be taken not to trample vegetation, some of which is found only in the Pasayten and then only rarely--such as the tusssocks west of Amphitheater Mountain. Please stay on the trail through here and resist the temptation to make a shortcut. Upper Cathedral Lakes offers excellent camping and is only a short skip away from Cathedral and Amphitheater. Remmel Lake also offers good camping.