Pinnacle Peak, Mountain summit in Mount Rainier National Park, Washington, United States.

Pinnacle Peak is a 6,562 ft (2,000 m) summit in the Tatoosh Range of Mount Rainier National Park, the range's second highest peak. The trail reaches a saddle with views of Rainier; the final stretch to the top requires scrambling and rock climbing. The Castle stands 0.2 miles (0.32 km) to the east.

A fire lookout station once operated at the summit from 1928 until 1971, with concrete foundations still remaining from the structure. This facility was part of a broader fire detection network that served the park's protection needs.

The trail to the saddle and summit is named for Cal Magnusson, a Cascade mountaineer who spent 25 years working with climbing expert Jim Whittaker at REI. Hikers on the route pass The Castle, a rock formation 0.2 miles (0.32 km) east of the peak.

From the trailhead, the route climbs to the saddle below the summit; the final stretch requires scrambling and rock climbing, so allow time for it. The Castle stands 0.2 miles (0.32 km) east of the saddle. Snow on the west side of the Cascades is wet and heavy, and summer often brings little cloud cover.

This peak rises from an extinct volcanic cinder cone that was partially buried by an ancient mudflow from Mount Rainier. The geological forces that shaped this landscape thousands of years ago remain visible in the terrain today.