We hadn’t seen another soul for a couple of hours.

That solitude is partially what we came for, and the St. Croix River was delivering.

“We’re not that far from civilization, are we?” my sister, Courtney, asked as we paddled down the placid river, lined by dense, green forest.

“No, not really,” I replied. The Twin Cities were about 70 miles to the southwest.

“I didn’t think so. It sure feels like it,” she said, before we both returned to our silent paddling.

We were on the first day of a three-day, 35-mile kayaking and camping trip along the 250-mile St. Croix National Scenic Riverway, which forms part of the border between Minnesota and Wisconsin. I had been eyeing up the riverway for a trip for a while, as it met all of my criteria for a great outdoor adventure: relatively remote, easy for a semi-beginner like my sister, plentiful backcountry campsites, and all of it free of portages, permits and fees. (Take that, Boundary Waters.)

Long before recreational paddlers plied the waters of the St. Croix and Namekagon (a tributary that is also part of the riverway), Indians used the waterways as transportation and trading routes. In the 17th century, French fur traders made their way to the rivers, followed by lumber companies in the 1800s. More than 60 dams were built on the St. Croix to control the river’s flow. Logjams were a regular occurrence, especially at the sharp bend in the river at the Dalles of the St. Croix.

By the 1960s, the riverway was a favorite for fishing. Wisconsin Sen. Gaylord Nelson and Minnesota Sen. (and future Vice President) Walter Mondale helped pass the Wild and Scenic Rivers Act in 1968, creating the St. Croix National Scenic Riverway. The idea was — and still is — to keep the rivers as wild and free-flowing as possible. Thanks to that act, the stretch we paddled — about 35 miles from Grantsburg, Wis., south to St. Croix Falls, Wis. — is indeed mostly wild and free.

Serene solitude

After staging our car in St. Croix Falls, we caught a ride with Jerry Dorff of Wild River Outfitters north to Grantsburg.

Dorff has been renting canoes and kayaks along the riverway since 1990. We peppered him with questions about the river: Are the campsites easy to spot? (“Yes, once you get your ‘river sense.’ ”) How are the landings after the July floods? (Almost all were open again.) Anything else we should know? (“Do you have bug spray?” — Dorff’s most prescient advice, we would later learn.)

We started our trip at the landing off Hwy. 70, where another pair was setting out in a fully loaded canoe. After we passed them near some riffles (small waves) a few miles downstream, we wouldn’t see anyone else until we stopped for lunch a couple of hours later.

What we did see: a bald eagle, perched on a partially submerged log near an island. Courtney floated within 20 yards of the bold beauty, who was completely unperturbed by our presence.

The dozens of turtles we passed throughout the day were less brave, sliding into the water from their sunning spots whenever we got close.

With a relatively strong current — about 3 mph — we alternated between leisurely paddling and simply floating, passing mile after mile of heavily forested shoreline, sometimes rimmed by the reddish sand that lined the river bottom.

Those forested shorelines were our backdrop for most of the 18 miles we paddled that day. It was a tree-lined ribbon of paddling paradise.

Campsite hopping

By early afternoon we reached Sunrise Ferry Landing, where a well-maintained group of campsites are open on a first-come, first-served basis. The riverway features dozens of similar primitive campsites at regular intervals.

Another group had claimed the landing’s prime site on a small bend in the river, so we set up at one of the others, a nice open site with peeking views of the river.

Sputtering skies and swarms of mosquitoes quarantined us in our tent for most of the evening. A Jurassic Park-sized dragonfly provided some entertainment (and redemption) as we watched it pick off the bloodthirsty monsters outside our screened-in sanctuary.

The next morning we set off on the mercifully bug-free river again, paddling around small islands, along densely wooded shores and past a four-canoe raft floating lazily.

Dorff had warned us that the campsites closer to St. Croix Falls are more popular, especially on weekends as pontoons and fishing boats putter upstream. We began to see evidence of that as we passed Wild River State Park on the Minnesota side.

A smattering of campsites after river mile 61 were occupied (including a beauty on a small peninsula), and river traffic picked up just a bit.

A stellar campsite beckoned us at river mile 58.5. Perched on the western bank, we had a terrific view of the St. Croix along with a shallow, sandy area for washing off two days worth of bug spray and sunscreen.

The mosquitoes were much less of a nuisance at this site, and we waved to a handful of passing boats and canoes before falling asleep under a blanket of glittering stars.

Even with a slower current, our final day on the St. Croix was a breeze as we paddled four miles to the landing at Lions Park north of St. Croix Falls.

This stretch of the river features more development as well as roads along both of its banks. But even the docks and the rumble of Harleys couldn’t distract from the river’s beauty. After we passed the four-pack canoe crew another time, we once again had the river all to ourselves.

If you go

Primitive campsites are available free on a first-come, first-served basis. Free permits are required south of the dam at Taylors Falls, Minn., as are portable camp toilets. The St. Croix National Scenic Riverway Visitor Center in St. Croix Falls, Wis., provides permits and more information; nps.gov/sacn or 1-715-483-2274.

Wild River Outfitters in Grantsburg, Wis., rents canoes and kayaks. They also offer shuttle service; ours cost about $100 for two people and two kayaks; wildriverpaddling.com or 1-715-463-2254.

Eric’s Canoe Rental in St. Croix Falls offers day trips and overnight trips; ericscanoe­rental.com or 651-270-1561.

The Dalles of the St. Croix is one of the most scenic stretches, but you’ll have to portage 1¼ miles around the dam or visit it separately. Wisconsin’s Interstate State Park provides a terrific view.

Getting there: St. Croix Falls is about 50 miles northeast of the Twin Cities via Interstate 35 and Hwy. 8.