The weekend trips we take during the school year and the weeklong Spring Break ski trip we take to Colorado are all great. But the photo albums that set on our living room coffee tables and the memories we will carry with us for the rest of our lives are from our Summer Expeditions to major national parks in distant corners of America.

It is hard to believe that at the ages of 15, 16, or 17 we have backpacked into the depths of the Grand Canyon, to the vast reaches of the Wind River Wilderness, and along the Continental Divide in Glacier and Rocky Mountain National Parks. Seeing a grizzly bear, a mountain lion or a buffalo close up raises the hair on the back of our necks like nothing else could. Wading up the Virgin River Narrows in Zion, negotiating a snowy slope

high in the Tetons, and paddling past moose and beaver in the Boundary Waters make us all want to spend our lives crusading to preserve these special places so kids will always be able to see the same things.

Many of the sights which we will remember all our lives were not even in the national parks we went to visit. Cowboys tending their cattle high on the lonesome Wyoming plains, Amtrak passenger trains carving through the Colorado Rockies, and gigantic storms bearing down on us out on the Kansas prairie are like something out of a movie. It's all still out there.

Wyoming calls itself The Big Country but in truth the whole nation is a big country. The various parts of America may as well be different continents.

There have been some difficult times on these trips. We have been pinned down for 24 hours by a blizzard in Glacier National Park. We had to hike up out of the Grand Canyon in 120 degree heat. And we had so many snowfield crossings and icy stream wadings in the Wind Rivers that several of us had to buy new hiking boots when we got home. But once we're back home and back in school, we wish every day we were back out there.

These really are major expeditions and they take an incredible amount of planning. We start that planning in September. We decide where we want to go the next Summer and start working out the itinerary. Sometimes we have to apply for trail permits nine months in advance, especially for the Grand Canyon and Glacier. Outpost 400 has a considerable store of equipment, but many of us prefer to use our own, so if we need a pack, tent or sleeping bag we ask our families to see those as potential Christmas or birthday gifts. We order current books on our destination and use long winter nights to read up on the place. We work to earn the money to pay our share of the trip cost. And we spend a lot of time in the gym getting in condition for 10 days on the trail.

l. Wind River Wilderness. Unbelievable. Largest remaining wilderness in contiguous United States. Glaciers. Snowstorms in July. Mountain Lions and Moose. World's greatest trail network.

2. Grand Canyon. No picture does it justice. Sheer vastness overwhelms. Miracle of light. You can watch one cliff totally change every 15 minutes as the sun moves across the sky. Stand on the rim and look down on thunderstorms far below.

3. Glacier National Park. Worth the trip just for the Grizzlies. Even when you can't see them, you know they're there. Greatest lodges of any national park. Going To The Sun Highway is an engineering miracle. Amtrak stops at three lodgings in park.

4. Yellowstone. Go for the Geysers, but stay for the world's largest, most diverse wildlife refuge. Buffalo, grizzlies, elk and eagles. Areas scarred by forest fires have grown back into magnificent young woodlands. Don't miss the mudpots and Yellowstone Falls.

5. Grand Tetons. The world's most beautiful mountain range. The eastern side of this park fronts on beautiful lakes, Yellowstone Park and the Jackson Hole yuppie colony, but the western side is rugged mountain wilderness as wild as anything in the Himalayas.

6. Rocky Mountain National Park. The front side and Estes Park absorb all the Denver crowd but the back side is more beautiful with far fewer people. If Grizzlies scare you away from northern parks, this is your paradise. Two easy days drive from Kentucky.

7. Zion. Two of the world's top 10 day hikes. You walk waist deep up the river through the Zion River Narrows, then hang on by chains a thousand feet up to reach Angel's Landing.

8. Bryce. Geologist's Disneyworld. Most bizarre and beautiful rock formations on the planet. This is where professional photographers come on vacation. A dayhiker's paradise.

9. Boundary Waters. World's greatest stillwater canoeing. Paddling wilderness too vast to cover in a lifetime. Great 1930s cabins for rent. Moose, loons, wolves, bear.

10. Isle Royale. No vehicle access at all; reachable only by ferry. 40 miles long, five miles across, one wilderness lodge and 200 miles of trail. America's largest wolf population. An island in the middle of Lake Superior. Few visitors.