As you sit in that Winnebago jam on the way to the Grand Canyon, you may find yourself muttering, "I wish there were a different big hole we could stand at the edge of!" Here are a few even more impressive than Arizona's Big Ditch.

AARP MEMBER DISCOUNTS SEE MORE

Subscribe to the AARP Travel Newsletter

1. Morning Glory Pool, Yellowstone National Park (northwestern Wyoming)

There's something terrifyingly primal about this 26-foot-wide puncture wound in Yellowstone National Park's Upper Geyser Basin. The gentle outer slope, colored brilliant yellow and orange by bacteria in hot water, plunges into a funnel-like darkness at its center. While you're in the area, take a walk along the paved 1.4-mile Morning Glory Pool trail, which passes some of the park's biggest geysers. Eruption times are posted at Old Faithful Lodge.

2. Hells Canyon (Idaho-Oregon border, near Copperfield, Oregon)

Tucked away along the Snake River in the northwest wilderness seven hours east of Portland, the deepest gorge in the U.S. is more than a half-mile deeper than the Grand Canyon. Plus, Hells Canyon is just half as wide, so the plunge is even more dramatic. Don't miss the vista of distant snowcapped mountains and steep valley walls at Hells Canyon Lookout, the overlook closest to Interstate 84 at Baker City, Oregon, 82 miles away.

Meteor Crater near Winslow, Arizona
The Meteor Crater is more than 550 feet deep. Jonathan Blair/National Geographic Creative

3. Meteor Crater (near Winslow, Arizona)

As you drive along the six-mile road south of I-40, the horizon darkens with a rugged rise. Step to that rim and your senses are overwhelmed with a vast, devastated landscape. Just 50,000 years ago a meteorite about half as long as a football field slammed into this area, killing untold woolly mammoths and excavating a mile-wide crater that looks like it was somehow transplanted from the moon. If you visit Meteor Crater, look for the cutout figure at the crater's floor, representing Apollo astronauts who practiced their moonwalks here.

4. St. Croix Dalles Potholes (Wisconsin-Minnesota border, near Taylors Falls, Minnesota)

Big-city drivers may disagree, but the deepest potholes in the world pepper a 20-acre spot in Interstate State Park, which is an hour north of Minneapolis. Here, an ancient river running from Glacial Lake Duluth carved hundreds of bores into solid basalt.