Devil's Dome Ross Lake East Bank Loop Trail is a 38.8 mile moderately trafficked loop trail located near Marblemount, WA that features a lake and is rated as difficult. The trail offers a number of activity options and is accessible from July until October.
A good ass kicker! They say 5 days, but I did it in 3 (not without a good amount of pain though). I did it last August, there was still snow at certain points, but was ok with trail running shoes, trekking poles and minimal weight (27 lbs. with food and water). This was my first intro to the north cascades and this is by far my favorite place to hike in the pacific northwest!