Mount Pete, Mount Peak, Pinnacle Peak, or the Cal Magnusson Trail: why can't we decide on just one name? Each name has history, and depending on if you're a local or a visitor, you may have heard a different name.
Originally, locals referred to it as Mount Pete, in honor of Pete Chorak, a Yugoslavian immigrant who settled in Enumclaw in the early 1900s, became a successful business owner, and donated some land to the town of Enumclaw. As the years wore on, "Pete" got misconstrued as "Peak", hence the newer name, Mount Peak.
Between 1928 and 1971, a fire lookout perched atop the mountain was called the Pinnacle Peak Lookout, thereby dubbing the summit with a third name: "Pinnacle Peak". The two trails that approach the summit even have their own names: The Cal Magnusson trail, and the more direct South Trail. But whatever you call this delightful dayhike in Enumclaw, you'll get to the same place; a beautiful site of a former lookout with views of the White River drainage and the jewel of the southern Cascades: Mount Rainier. Visitors can hike, bike, run or watch wildlife.
Following the Cal Magnusson Trail, hikers will climb 1000 feet in a mile, ensuring a healthy workout through thick forest. Hikers may find fascination in the basalt outcroppings just short of the summit; these are formed by the rapid cooling of lava tubes and are relatively common in the South Cascades, though always an interesting sight.
If you're inclined to take the South Trail, you can expect multi-user company. Mountain bikes are permitted on this old gravel road. Because of this, the grade is more forgiving. That, combined with views of the White River and Mount Rainier make this a gentler route, though there is elevation gain to be had as the trail enters the forest and approaches the summit. If you do elect to take this route, don't forget to take a look at the columnar basalt formations, visible just a little ways down the Cal Magnusson trail from the summit.
Once you've achieved the summit, take a look around the former lookout site. You can see old concrete footings that formerly supported the lookout. Now logs have been placed across these to serve as benches, where you can take a load off and enjoy the view, including Mount Rainier and much of the surrounding valley.
After you've had your fill of views, head back down, either the way you came, or try for a thru-hike by heading down the trail you didn't use on the way up. Keep in mind that if you opt to do this, you'll need to arrange a car shuttle or a key swap, but it means you'll get to explore this park to its fullest in just one day.
WTA Pro Tip: King County Parks has a great map of this park on their website.