fisherl has posted a similar question, about the route from Carson, WA, to Randle, WA, via the "back door route." Rather than hijack that thread -

We are planning to drive from Hood River to Ape Cave (southern Mt. St. Helens) in mid September. Rather than use I-5, we thought to cross over to the Washington side (how's the view from that side?), go 14 to Wind River Road at Carson, go north to WF-90, and on to the Ape Cave. Mapquest says good to go, seasonally, but if anybody is familiar "real world," I'd appreciate the input. Was concerned about the NF-90 piece at the turnoff.

On the way back, we'll go to I-5, as we will head to Portland for the night and then home. Thanks.

From the back of the GPNF map: "Ape cave was discovered in 1947 by a logger named Lawrence Johnson. However the cave was not explored until the early 1950's when a scout troop, led by Harry Reese, lowered a team of scouts down a 17 foot overhang to the cave floor. Located on Forest Road 8303 3 miles north of the junction of 83/90." More info at: http://www.fs.fed.us/gpnf/recreation...ve/index.shtml
Road 8303 has lots of switchbacks but is indicated to be paved.

Looking forward to it. Since we are coming after Labor Day, we have to provide our own lighting for the hike into the cave (vs. from Ranger Station). DH has been collecting some cool LED stuff, he just can't seem to stop. At least, if we lose power thanks to Irene, we'll have plenty of alternate light sources...

The Washington side of the Columbia River has a much smaller highway that is twistier and slower, but in my opinion, more scenic. Forest Rd 90 is a good (albeit curvy) 2-lane paved highway. The road from Carson to FR 90 (Road #30 then Road #51) is quite twisty and can be dusty, but otherwise is an OK road.

Ape Cave is fun. It is a short walk along a paved path to the entrance, then you drop down some metal stairs to the cave itself. You can then walk straight ahead, along a fairly smooth floor to the end of the upper cave; or go behind the stairs for a more lengthy exploration through the lower cave. The latter is a rougher trip, entailing climbing over or around some boulders and rocks along the way. It is great to have flashlights, but a lantern of some sort would be a good idea too. Much of the cave is quite large, so it is hard to get a feeling for that without a larger lantern or floodlight.

Reference: http://tinyurl.com/3kehexf

Consider going a little further along Forest Road 83 to Lahar and Ape Canyon, where there is a fine view of St. Helens and the mud/debris flows off the back side of the Mtn. Also, you can see exposed strata of many recent eruptions, with layers of ash and pumice.

Awesome, thanks for the advice.