| The Ironman Traverse is one of the most popular problems in The Buttermilks. This boulder not only hosts THE v4 testpiece, it also features a v2 crack problem, a v7 dyno (The Iron Fly), and The Iron Cross at v6 (traverse The Ironman and then back across the top). This boulder boasts something for everyone. A must do boulder. Climber-Chris Morrison. Photo-Al Amores.