BOB MARSHALL WILDERNESS, Mont. — As Scott Bosse launched his packraft in Youngs Creek, it felt as if gravity disappeared.

“I find it tremendously liberating,” Bosse said of packrafting.

For the previous day and a half, Bosse and a group of five other packrafters had been lugging 50-pound backpacks up and over Youngs Creek Pass to access the Bob Marshall Wilderness and eventually reach Youngs Creek, a tributary of the South Fork Flathead River.

Along with tents, sleeping bags, food and other typical backpacking gear, each person in the group also carried a packraft, a small, packable, inflatable single-person raft.

When they reached a spot on Youngs Creek where the water began to look high enough to float, they all set down their packs, rolled out their rafts, inflated them and began their 45-mile float that would take them down the South Fork to Meadow Creek Gorge.

Packrafting isn’t new, in fact it’s been around for centuries, but it is seeing a boom in popularity.

“I would say it’s exploding,” said Brad Meiklejohn, president of the American Packrafting Association.

The APA has more than 1,000 members. About a year ago, its membership was half that.

Packrafting offers a different way to look at backcountry travel.

“Who thought you could ever have a boat in your pack that weighed less than five pounds,” Meiklejohn said.

For most backpackers, lakes and creeks are barriers, said Bosse, who works as Northern Rockies director for American Rivers in Bozeman. The opposite is true for rafters and kayakers, for whom land is a barrier.

“In the wilderness, you either travel by land or you travel by water,” Bosse said. “With a packraft, you can do both.”

Packrafts also allow adventurers to float wilderness rivers without needing a pack string to carry a full-sized raft, said Jared White, the Wilderness Society’s regional communications manager in Bozeman.

“I just seems like it’s been the best new invention/technology for wilderness travel that I’ve seen in my lifetime,” White said.

While the idea of carrying a small boat to be able to cross rivers and lakes dates back to native cultures around the globe, the more modern resurgence of packrafting got its start in Alaska.

“The roots of packrafting are a little hazy but go back quite a ways,” Meiklejohn said. “Here in Alaska, they’re ideal for our country.”

With few roads in the state and a lot of rivers, backpackers inevitably will run into a big body of water.

“If you don’t have a boat, that’s the end of the trip,” said Meiklejohn, who lives in Eagle River, Alaska.

Meiklejohn started packrafting nearly 20 years ago.

“I came to this from a backpacking background,” he said. “I just needed some way to get across rivers.”

“That’s what’s particularly appealing about these boats is they really open up entire landscapes,” he added.

Initially, Meiklejohn’s solution was kiddie pool toys. Usually he could get those to last about a week, patching them each time he hit a stick or a rock in the river and ripped a hole in the thin plastic.

“If I treated it really carefully I might milk it through a whole trip,” he said.

In the ‘80s, a couple of companies released packrafts, but they were designed for lakes and weren’t durable enough for rivers, said Sheri Tingey, owner of Alpacka Rafts, a Colorado-based company that makes packrafts.

“The thing with (those) was it was not if you’re going to sink, it was when you’re going to sink,” Tingey said.

Tingey was inspired to start her own packrafting company after her son took one of those lake-designed packrafts on a river trip in Alaska.

“They didn’t really float as much as they swam for two and a half weeks,” she said.

The following summer, a different raft didn’t hold up any better.

“When he got back from that trip, he said, ‘Can you build me a boat that works,’ and like a fool, I said, ‘Yeah, I can do that.’”

Tingey, who worked making ski clothes and other outdoor gear, spent that winter designing a light-weight packable boat made to float a whitewater river.

In 2001, she decided to launch Alpacka Rafts.

The rafts are designed to be lightweight and easy to carry, but also capable of tackling major rapids.

“People are using these boats in Class IV and V whitewater,” Meiklejohn said.

Packrafters have done first descents of rivers that otherwise would be pretty hard to get to, he said. Some packrafters can even do an Eskimo roll in a packraft.

Alpacka’s rafts weigh anywhere from three and a half to six pounds. With the addition of a paddle, helmet and flotation device, the whole set up adds about 10 pounds to a person’s pack.

Several manufacturers have cropped up making packrafts. Some companies specialize in smaller boats or ultralight boats or inexpensive boats. One company makes a packraft so small that it rolls up to the size of a Nalgene bottle.

While the rafts are great for backcountry trips, they have other uses as well.

“You can roll it up and put it in the overhead bin and fly anywhere in the world,” Meiklejohn said.

Packrafts are also great for families doing front-country floats because they’re so light and easy to carry.

White likes to take his packraft on nearby rivers for quick, easy floats.

“A roadside river can be a great thing to do in a packraft after work,” he said.

Since starting Alpacka Rafts, the business has grown steadily. The first couple of years, 90 percent of the boats Tingey made were sold in Alaska. Now she sells packrafts all over the world.

“It’s just been a slow, steady movement,” she said. “It’s never going to be a giant niche. Everybody in the world does not need a packraft. What it is is a wonderful addition to a quiver of boats.”

Over her 13 years in business, Tingey has seen a shift in her customers. Originally, people bought packrafts merely as a way to get across rivers. They were backpackers, adventure travelers, climbers or mountain bikers who needed a way to access the areas where they wanted to practice their sport.

“They were not water people,” she said. “They were people looking for a way to get across the water.”

That has changed in recent years.

“Now people say, ‘I’m a packrafter.’ They actually plan packrafting trips,” Tingey said. “That’s their sport.”

Packrafting, in and of itself, is a sport for White and Bosse.

White got started in the sport three years ago after a friend talked him into trying it. He was hooked instantly.

For White, packrafting is another way to experience wilderness.

“You can’t really know a place unless you travel it by river,” he said. “It’s sort of the artery of the land.”

When White started packrafting three years ago, the sport was fairly unknown in Montana.

“Once upon a time, I couldn’t find anyone to packraft with,” he said.

That’s not a problem anymore.

And he now gets fewer questions when floating in his bright blue, toy-looking, small boat.

“Three years ago, nobody recognized them,” he said.

The rise in the number of packrafters accessing wilderness is something the American Packrafting Association is keeping an eye on.

“We are apprehensive about the flood of packrafters that are headed out into the wild in these boats,” Meiklejohn said.

Some land managers are also apprehensive about this growing sport and are struggling with how to regulate packraft use.

“Because this is a new use, a lot of land managers are struggling to get their heads around it,” Meiklejohn said.

APA is working to promote safety and conservation ethics.

“We are conservationists,” he said. “We want people to be respectful users when they’re in wild places.”