Most years I take students on a field trip to Yosemite National Park.  You can see photos from previous trips on various pages on my website.  The National Park Service staff there do an exceptional job of hosting us when we go.

I have a number of links that student use to learn about the Park prior to our visit.  You can find them Yosemite & Nature.

I’ve just added a site to that section, which is a New York Times slideshow on Ansel Adams photographs of the park. I learned about it from the fine blog Free Technology For Teachers.