Mount St Helen's from Portland to Seattle
 

We are visiting Seattle in July but will be flying into Portland. We will be leaving Portland early in the morning driving to Seattle. We wanted to stop at Mount St Helen's on the way. Is this feasible in one day? From what I can see it is, but I don't want to be over ambitious. Is there anything else that you would suggest we do along the drive (Mt Rainier etc.)? If it helps we would not spend a lot of time hiking etc., we just want to get a feel for the area.

I think Mt. St. Helens is a perfect place to visit on your way to Seattle. Run a search on this website and you will find a lot of information.

That said, the beauty of Mt. Rainier is incomparable. It is a significantly longer day trip for your route, and I think you'd feel cheated not giving it more time.

It is 170 miles from Portland to Seattle on I-5. The drive to Mt. St. Helens visitor centers is 50 miles each way on a two-lane road. This requires a full but very doable day.

It is a full day, but there are three National Park Service Visitors Centers accessible by the western entrance off of I-5 (at Castle Rock) and the first one, the Mt. St. Helens Visitors Center, is probably 5 minutes from the exit. You should stop here to buy park passes, but moreso, to see the exhibits on the volcano and the slideshow/film on the eruption. Plus there is a pretty short walk here.

Next up is the Coldwater Ridge Visitors Center. It focuses on the return of the wildlife and plants, and it has a short nature walk on a paved trail.

Then you drive past the new lake and can picnic there and hike if you have time. It is very pretty and fairly flat around the lake.

Then it's up to the Johnston Ridge Observatory which is as close to the crater as you can go. Here the exhibits focus on the geology and there is a terrific movie that will give you goosebumps. There is a great walk here on paved paths, through the moonscape near the crater, which is not too far away. This is the center that is about 50 miles from the exit.
It is indeed a full day, but it is broken up by lots of educational stops and little walks, plus your picnic lunch (do bring one, as the food is quite limited).

The drive itself, up the mountain, is far from boring. With each turn in the road as you approach the volcano, you are rising and getting closer to the blast zone, so it does not lack for suspense.

I do think it is a perfect day trip - a total package. We used to count on a 12 hour day from Portland, so count on an extra hour for the extra distance up I-5 to Seattle. It is just under an hour north of Portland. You are pretty far north and will have light to 10:30 at night, so you can make it down the mountain before dark.

If you don't already, you will really appreciate the National Park Service after this trip!

http://www.fs.fed.us/gpnf/mshnvm/
Look for the westside entrance.

You are perfectly situated for a visit to Mt. St. Helen's driving from Portland to Seattle. I believe Seattle will be 4 1/2-5 hours north of Mt. St. Helen's. My wife took a day trip with a boyfriend of her's a few years ago and tells me it is well worth visiting.

Seattle is two hours north (or less) of Castle Rock, the west entrance. It is farther from the other two entrances, and I imagine Shane is referring to the northern entrance, which is near Mt. Rainier.

Thanks everyone, this is very helpful. It looks like we can accomplish our visit to Mt St. Helen's.