My family's fascination with volcanoes can be traced back to an afternoon walk in autumn of 2004. While strolling in our Portland, Oregon, neighborhood, my son Cobi, then age 3, and daughter Izzi, 1, and I stopped to gaze at one of our favorite views: the lovely snowcapped, flat-topped Mount St. Helens in neighboring Washington. Suddenly, a huge steam plume, like chimney smoke, rose from the crater.

"Wow!" Cobi exclaimed.

"Wa," Izzi echoed.

"Whoa!" I cried. I remembered 1980, when that same volcano literally blew its top, leaving itself 1,300 feet shorter and sending a plume of ash billowing 15 miles into the air.

Fortunately, what we saw that fall day was a sign of far less destructive forces. In 2004, Mount St. Helens began pumping out masses of hard lava, often accompanied by plumes like the one we witnessed. These slow-motion eruptions, which continued until this past January, didn't destroy the mountain like that earlier blast, but actually helped rebuild it instead.

Cobi was full of questions about what we'd seen, so not long after our walk, we took a road trip on Washington Highway 504 to the Mount St. Helens National Volcanic Monument for a closer look. What we found was so interesting that it even inspired me to write a children's book, "Will It Blow?: Become a Volcano Detective at Mount St. Helens."

The volcanoes located on the U.S. mainland aren't just the stuff of fascinating geology lessons, though. They also happen to be located in gorgeous, unspoiled national parklands that offer plentiful opportunities for hiking, picnicking, and oohing and aahing. Ready to explore our nation's volcanic treasures? Check out our tips for top hot spots, activities, and lodging options that will make your next trip a total blast.