The Northern Rocky Mountains are noted for natural tubing terrain in city parks and along mountain byways, but bring your own tube. Four areas, however, provide the tubes, aid repeated descents with lifts, and groom lanes for smooth sailing.

Sioux Falls, South Dakota: The region's biggest tube park sits outside Sioux Falls in Great Bear Recreation Park. Its popular Kirby Family Tubing Park saw over 17,000 tubing visits last season.

"Tubing opens up the area to nonskiers," commented park manager Dan Grider. "It requires no skill; you just sit down." Four lanes vary in pitch on 600-foot-long descents progressing from a gentle 10 degrees to a 40-degree drop. Riders sit on their tubes while a cable tows them back up hill.

Grider's philosophy for tubing, different from many other tube parks, makes daily tickets ($9 weekdays, $13 weekends and holidays) available for unlimited runs. "When I sell a ticket for tubing, I don't time it, because I want riders to watch skiing and get interested," he said. You can even tube into the evening under lights.

The tube park opens from 3 to 10 p.m. Mondays through Fridays, but on weekends and holidays, it opens earlier at 9 a.m. Kids shorter than 42 inches are permitted, but they must ride with an adult.

"There's lots of different ways to get deals on tubing," said Grider. The park sells season tubing passes ($129 per person), a 10-visit punch card ($150, and two-for-one tickets on Two For Tubing Tuesdays. Five-year-olds and younger tube free with an adult. Call (605) 367-4309.

Big Sky, Montana: Big Sky Resort debuted their tubing park two winters ago in their Family Fun Zone during Fridays, Saturdays, and Sundays from 3 to 7 p.m. Two lighted lanes race down a 500-foot-long course while a magic carpet totes riders carrying their tubes back to the top.

"We really wanted to complete the entire family experience that includes activities after the ski hill closes," said Dax Schieffer, spokesperson for the resort. "It's really popular for that time in between the ski hill and dinner." Big Sky expects to open tubing before the Christmas holidays.

Big Sky does not enforce any minimum age or height requirements for tubing, contrary to other resorts. Tickets last season ran $15 per hour for adults and $10 per hour for children 10 and under. Call (406) 995-5749 for updates.

Jackson Hole, Wyoming: King Tubes lights up at night on Snow King Mountain in Jackson Hole. Dine in town, drive five minutes to the hill, and you can be tubing. "It's the most convenient thrilling tube hill I've seen," said Adam Shankland for Snow King Resort.

Three lanes rip down the lower slopes of Snow King. Riders sit on their tubes to be towed back to the top via a surface lift. Five-year-olds can tube, but not kids less than 42 inches tall. "The greatest thing about any tube park is how it brings skiers and nonskiers together," said Shankland. "Our record age is a 90-year-old woman full of energy."

King Tubes, open 2 to 8 p.m. on weekdays and noon to 8 p.m. on weekends and holidays, aims open Dec. 13 thanks to snowmaking. Hourly rates run $14 for adults and $10 for children. A single ride costs $7. Call (307) 734-TUBE (8823).

Grand Targhee, Wyoming: What makes tubing at Grand Targhee different from anywhere else? "You're still in the heart of the Tetons enjoying the outdoors," said David Hudacsko, Grand Targhee Resort Public Relations Manager. "Tubing during the sunset is amazing."

Targhee may have only one 350-foot-long tubing lane, but it packs a punch. "The track has 15-foot walls and plenty of turns to keep it exciting!" said Hudacsko. The lighted hill is open daily from 2 to 7 p.m. Riders, carrying their tubes, walk onto a magic carpet to be whisked back up the hill.

"It's nice for families wishing to spend time together when they maybe haven't been together on the slopes," added Hudacsko. All riders pay $8 per person per hour and must be 42 inches in height.

Targhee's tubing opens for the season when snow conditions allow. Call (307) 353-2300 or (800) 827-4433.

Check out Paul Doherty's One Stop Guide For Snow Tubing, Sledding, And Snowplay for detailed information on snow-play areas throughout North America.