Index contains possibly Washington's best granite climbing. The routes range from shorter single-pitch routes to long 500'-high walls. Although the main attraction of the area for most is the spectacular crack climbing (fine-grained granite that makes gorgeous cracks that are much less abrasive than J-Tree or Leavenworth), there is also some sport climbing and many aid routes. Although rain can be an issue (it is western Washington), summer conditions are often ideal and some routes can still be done in a light drizzle.
Getting There
Drive east on Highway 2 and turn left onto the road that leads to Index Town. After the bridge, turn left at the stop sign and continue along the small road (past the shooting range). There will be a parking lot on the right. Out of the parking lot, you cross the train tracks. A couple more steps and the Lower Town Wall is right there. Other areas might require longer approaches.
This is the second pitch of Roger's Corner. Take the obvious handcrack next to the tree. Straightforward, fun jams. You'll wish this went on for another 150 feet. A bonus is that it stays dry in the rain. There is an anchor on the ledge above, and you can toprope Marginal Karma, the 11b immediately to the right, from those bolts. You can also approach this from the top of GNS if you don't want to go up Roger's....[more]
Everybody should get Darryl Cramer's excellent guide to the area, Sky Valley Rock. But for a temporary guide if you can't find his, try: http://www.stanford.edu/~clint/index/ Not as user friendly, but gives you an idea of the area.
This is probably one of the most underrated climbing areas around; I hope it stays that way. I learned to climb there; I hope the climbing and the town never change.