My buddy Paul and I completed the Issy Alps 50K Endurance Challenge! AND I finally got to stick a Peakery sticker on the infamous mailbox atop Mailbox Peak! The route is about 33 miles long and includes about 13,000' of elevation gain. It involves climbing Mailbox Peak, Mount Teneriffe, Mount Si (to haystack basin), and Little Si, connecting them all on foot. Although these are actually Cascade peaks, there are 100K and 100 Mile versions of the challenge that extend into the Issaquah Alps range, boasting much more elevation gain.