There are two big holes along Highway 31 in Central Oregon: Big Hole and Hole-in-the-Ground. Both are maars, or craters left behind by volcanic steam explosions. If you've only got time to see one maar on your drive across the state, choose Hole-in-the-Ground. It's located just a few miles off the main road. And, from the parking area, you can see the entire circumference of the giant crater. Low shrubs and pockets of trees dot the interior of the crater, but its shape is unmistakable. Big Hole, in contrast, is shrouded by tall, thick trees that hide the overall shape of the landscape.
Hole-in-the-Ground is about a mile wide and 400 feet deep. One trail encircles the crater and two others plunge down into the center of the hole. Although it looks strikingly similar to a meteor impact crater, it is one of many signs of the area's rich volcanic history. Walk around the edge of the crater to get a panoramic view from all sides. Or, wander down into the crater to gain a new perspective. Chances are you'll have the place to yourself.
The crater is accessible year-round, as long as the roads to the rim are not blocked by snow.