Approach notes

Park at a large pullout on the south side of 1A, just west of the Protection Valley Campground entrance. Walk back east about 5 min then head north into the Protection Mountain Campground (there is a gated CN driveway directly across the road). Continue through the campground, passing site 53, a cook shelter on your right, and a MAXIMUM 20 speed limit sign, until you reach the power lines., Head east another 100m before turning north into the forest. If no one's been in yet, use your tracking skills! A track has been established, the softer ground is compressed in places, branches broken off trees, etc., but the following might help.

Hike through uphill rolling terrain, crossing several small drainages, and some benches, trending toward the valley proper. Continue steeply up the west edge of the drainage. Eventually you will cross 2 or 3 small drainages and soon you will drop steeply down into the Protection Valley drainage proper. Hike up the drainage for a short way, then cross and begin ascending boulders and talus up to the west end of Castle Mountain. You want to get high enough that you can climb through a couple rock steps and complete a rising traverse north into the valley.

Doing this approach onsite, in the dark, will be exceedingly difficult. If you've never been up there, taking some time to scope out the approach ahead of time will be useful