It’s hard to decide where to look at the Interstate state parks in Wisconsin and Minnesota.

Look up to take in views of the steep basalt cliffs along the St. Croix River in the gorge known as the Dalles of the St. Croix, and you miss the deep, circular potholes drilled into the rock below your feet.

Look down at those cavernous depressions and you miss the churning of the rapids far below, or the weathered face of the Old Man of the Dalles, a prominent rock formation standing watch over the gorge from the cliffs.

The Old Man watches over the river from a bluff on the Wisconsin side — the river serves as a border between Wisconsin and Minnesota, and each state manages its own side of Interstate State Park.

Wisconsin’s Interstate, the larger of the two, is the state’s oldest state park, established in 1900, and is still one of its finest. It sees its share of visitors — more than 350,000 last year — but it’s probably better known to Minnesotans, with the Twin Cities less than 60 miles to the southwest.

Miles of trails — including the eastern terminus of the Ice Age Trail — wind through the 1,400-acre Wisconsin park, many providing fantastic views of the dramatic gorge. Add in a national scenic riverway for kayaking and a small lake for swimming and this gem of a park is ripe for exploring.

The area has long been a draw to tourists, dating back to the 1800s when steamboats brought visitors up as far as the rapids at St. Croix Falls, Wis., and Taylors Falls, Minn.

The tourists often competed with, and sometimes gawked at, the “river pigs” who guided massive pine logs down the St. Croix to sawmills in Stillwater.

This part of the St. Croix was especially good for gawking, as a nearly 90-degree turn in the gorge here led to massive logjams, including one in 1886 that stretched back for two miles. Tourists stood on the huge piles of logs, snapping photos as river pigs used every means possible to untangle the jam. It took 200 men six weeks to bust it open.

Before the lumber barons were jamming up the gorge, fur traders and Indians, including the Ojibwe and Dakota, plied its waters.

The Old Man of the Dalles has watched them all from his perch. But he hasn’t seen everything in this park’s tumultuous natural history. He was late to the game, relatively speaking, and didn’t come into existence until long after the red-hot lava that flowed up from the Earth’s core hardened into the park’s distinctive black rock.

No, the Old Man isn’t so old after all. He most likely came into being about 10,000 years ago, when the last glacier began receding. As it retreated, the meltwater gushed south. The fast-moving, mile-wide glacial river chipped away at the hard basalt rock to carve the deep gorge and its rock inhabitants.

Border battle

Minnesota’s 281-acre Interstate park possesses similar rock formations and even more dramatic glacial potholes. The circular holes and depressions in the rock, some dozens of feet deep, were formed when that glacial river covered the rocks here, and sediment in swirling eddies and whirlpools drilled holes into them.

Minnesota’s side is home to the world’s deepest explored pothole, the Bottomless Pit, which goes down 60 feet. The park may be home to even deeper potholes, but they have yet to be excavated (many are filled with silt, rocks and water).

Wisconsin’s potholes are more modest but still impressive. These unique formations are part of both a state natural area and the Ice Age National Scientific Reserve, which protects glacial landscapes across the state. They’re also part of the 250-mile St. Croix National Scenic Riverway.

Things to do

Hiking along the gorge is a must, obviously.

The 0.4-mile Pothole Trail loop on the Wisconsin side provides some of the best views of both the river and the craggy cliffs of the gorge. The trail is also littered with glacial potholes, which are not fenced off. Keep an eye on kids, dogs and your own feet when hiking.

At the start of the trail, look for the rock denoting the western terminus of the 1,200-mile Ice Age National Scenic Trail.

Another 9 miles of hiking trails wind through the park, including the 0.8-mile Eagle Peak trail that climbs to the park’s highest point for an overlook of the surrounding valley — best viewed while the leaves are down.

Hike the short half-mile Ravine trail for a look at one of the stone buildings constructed by the Civilian Conservation Corps in the 1930s. The CCC had a camp at Interstate and not only built many of the trails and buildings still used today, but also helped reforest much of the surrounding land that had been plundered by the loggers.

Note that most of the trails in the park are rugged, with rocks, steps and some steep climbs. Loose gravel, leaves, mud and ice can make for slippery surfaces and challenging hikes at times.

Be sure to leave time to explore the St. Croix River and its gorge from below.

The St. Croix National Scenic Riverway offers countless opportunities for fishing, kayaking, canoeing, camping and wildlife viewing along its route.

In Taylors Falls, Eric’s Canoe Rental (651-270-1561, ericscanoerental.com) provides canoe and kayak rentals plus shuttles for trips along the St. Croix. The 7-mile trip from St. Croix Falls south to Osceola, Wis., is a nice, easy two- to three-hour trip.

For a more passive trip, take a tour aboard paddle wheel boats with Taylors Falls Scenic Boat Tours (651-465-6315, wildmountain.com). Daily tours of 45 or 80 minutes begin May 6.

Back inside the Wisconsin park, the shallow, 25-acre Lake O’ the Dalles has a small beach for swimming, with a launch for nonmotorized boats. Find a boat launch on the St. Croix near the south end of the park.

Interstate has about 60 campsites on the Minnesota side and two family campgrounds with more than 80 sites on the Wisconsin side. Wisconsin’s north campground offers flush toilets and showers, but you’ll get a more serene experience in the rustic south campground (pit toilets only), away from the traffic noise of Hwy. 8.

Getting there

Minnesota’s Interstate State Park is about 50 miles northeast of the Twin Cities at Taylors Falls, via Interstate 35 and Hwy. 8.

Wisconsin’s Interstate is just across the St. Croix River from Taylors Falls, and just south of St. Croix Falls, Wis.

More information

You’ll need a state parks admission sticker to get into each park: The Minnesota side costs $5 a day and $25 a year; Wisconsin’s park is $8 daily and $28 annually. Because the Wisconsin park is part of the Ice Age National Scientific Reserve, national parks passes are also accepted there.

Minnesota: 651-465-5711 or dnr.state.mn.us/interstate.

Wisconsin: 1-715-483-3747 or dnr.wi.gov/topic/parks/name/interstate.