Whetstone Peak to Opal Creek Loop is a 15.8 mile moderately trafficked loop trail located near Elkhorn, Oregon that features a great forest setting and is rated as moderate. The trail is primarily used for hiking and is accessible from May until October.
I like loop trails. Did this one in April, though the east side of the Peak was covered in deep snow. There's no real water source on the hike up, but the far side of Whetstone has a few streams before you reach Battle Axe creek, though likely seasonal. The Whetstone peak climb was poorly maintained (as of 4/16). The lower trail system before you get to Opal Creek has a number of choices. They all pretty much go the same place at the end...the Interpretive Center.