If you know, ultrarunning, then you have heard of the HURT100. A race that takes place on the island of Oahu in Hawaii that consists of five, 20-mile loops, each loop containing a couple out-and-backs. Each loop have approximately 5000 feet of elevation gain. in the mountainous jungle in Honolulu. It is known to have technical terrain consisting of a lot of roots and rocks making it difficult to run. Easily the most iconic route on the island of Oahu.
 

This route traverses from the highest point in the Muddy mountains, to muddy mountain peak, and back to the trailhead. This route connects two of the most significant portions of the Muddy mountains, that sit directly east of Las Vegas. This route would be best to complete in colder temperatures, to avoid the scorching sun in the summer. 

Embark on the Anniversary Narrows and Anniversary Peak Hiking Loop in Nevada, a trail that combines diverse landscapes and challenging terrain. Start at the trailhead, surrounded by Nevada's rugged terrain. The route takes you through Anniversary Narrows, a slot canyon with towering rock walls. The trail then leads to Anniversary Peak, a summit offering panoramic views. The descent covers alpine meadows and pine forests, providing a varied Trail running and hiking experience. 

This is a beautiful route in the Pacific Coastal Range of California that is extremely popular locally and is in a reserve managed by the University of California, Davis. After a brief flat start there is a steep climb with switchbacks up the majority of the almost 1500 ft elevation gain to the ridge where there are excellent views of California's Sacramento Valley on one side, and Lake Berryessa and the Pacific Coastal Range on the other. The trail travels along the ridge with occasional rock scrambling as it goes up and down over small crests in the ridge.

This loop travels into the heart of the Ansel Adams Wilderness to almost the boundary of Yosemite National Park.  You will have impressive views of Mammoth the Eastern Sierra and the Lyell region of Yosemite.  Part of the loop requires traversing the saddle of Triple Divide Peak from Slab Lakes over to Turner Lake.  It is class 2 terrain and as long as you work your way down to Turner Lake, you can head directly up to the Post Peak Pass Trail where you will gradually descend back to the trailhead at Fernandez.