I visited Crater Lake National Park in July of 2009.  It is about 370 miles north of Sacramento in Oregon.  We ended up staying in Klamath Falls, Oregon the night before we drove to the park.  On the way back, we stayed in Medford, and we enjoyed the tax free shopping.  Crater Lake was amazing.  It was created a long time ago when the volcano top blew off the mountain.  Over time, melting snow filled the lake, and it is the deepest lake in North America today.  No private boats are allowed in the lake, and the water is an amazing blue color.