The Issaquah Alps are a low (generally 2000-3000') range of mountains east of Seattle, WA. They include several popular day hike peaks, such as Mailbox Peak, Mt Si and Mt Teneriffe. The Issy Alps 50k, 100k and 100M were established by George Orozco as FKT routes for adventurous souls, as reported in Trail Runner Magazine. A website outlines the routes and the "rules", and a list of finishers for each distance is kept here. Running a yo-yo of the 50k is another Variation.