Up to your snorkel in snow

Sunset, Wntr, 1992

Bring your snorkel, they say--for skiing. Skiing in powder that's unpacked, ungroomed, and piled too deep to bother measuring.

Rooster-tailing through dry, feather-light powder is the ultimate thrill for a downhill skier or snowboarder. And Western resorts cater to these adventurers with guided excursions that go beyond the bounds of lifts and trails.

These powdery playgrounds are accessible on three types of excursions: snowcat trips, helicopter expeditions, and "off-piste" (off-trail) guided tours. Over the course of a day, snowcat or helicopter service will let you make as many as six runs, descending a thigh-burning total of 10,000 feet or more. Guided, European-style tours take you beyond resort bounds into "double black diamond" terrain of pristine slopes and bowls.

Except for introductory tours, expect these trips to be geared to expert skiers. And be prepared for the possibility of avalanche. All guides have expert avalanche training; you're provided with a rescue transceiver and, on some tours, a lightweight shovel and survival pack. Call to verify this season's prices.

Snowcat skiing

Colorado. Aspen Mountain, Box 1248, Aspen 81612; (303) 925-1220 or (800) 525-6200. Cost: $200 per person.

Crested Butte Mountain Resort, Box 3001, Mount Crested Butte 81225; (303) 349-2222 or (800) 544-8448. Tours based from nearby Irwin Lodge. Cost: $160; $262 with lodging.

Monarch Ski Resort, 1 Powder Place, Monarch 81227; (719) 539-3573. Cost (not including lift ticket): $80; $60 half-day; $20 single run.

Ski Cooper, Box 896, Leadville 80461; (719) 486-3684. Cost: $95; $50 half-day; 6 skiers minimum.

Steamboat: contact Steamboat Powder Cats, Box 772468, Steamboat Springs 80477; (303) 879-5188 or (800) 288-0543. Cost: $155; $195 with overnight at wilderness cabin.

Idaho. Brundage Mountain, Box 1062, McCall 83638; (800) 888-7544. Cost: $75, including lunch and lift ticket.

Montana. Big Mountain, Box 1400, Whitefish 59937; (406) 862-3511. Cost (not including lift ticket): $35 half-day.

Bridger Bowl: contact Montana Powder Guides, 15792 Bridger Canyon Rd., Bozeman 59715; (406) 587-3096. Guide rate for up to four people is $125, $25 per extra person; snowcat costs $300 for up to six people.

Oregon. Anthony Lakes Mountain Resort, 61995 Quail Rd., Island City 97850; (503) 963-4599. Cost (not including lift ticket): $10 half-day.

Wyoming. Grand Targhee, Box SKI, Alta 83422; (307) 353-2304 or (800) 443-8146. Cost: $135 to $155; $95 for half-day.

Helicopter skiing

Colorado. Telluride: contact Telluride Helitrax, Box 1560, Telluride 81435; (303) 728-4904. Cost: $425.

Vail, Arapahoe Basin, Breckenridge, Copper Mountain, Keystone: contact Colorado Heli-Ski U.S.A., Box 64, Frisco 80443; (303) 668-5600 or (800) 435-4754. Cost: $320 (introductory) or $400; $160 half-day.

Idaho. Sun Valley: contact Sun Valley Heli-Ski, Box 978, Sun Valley 83353; (208) 622-3108. Cost: $305 to $385.

Montana. Bridger Bowl: contact Montana Powder Guides (see listing above). The guide rate for as many as four skiers is $125, plus $25 each additional person; helicopter rate is $400 to $600 per skier.

Utah. Salt Lake City area resorts: contact Wasatch Powderbird Guides, Box 920057, Park City 84092; (801) 742-2800. Cost: $385. Or contact Utah Powderbird Guides, (801) 649-9739. Cost: $350 to $420.

Wyoming. Jackson Hole: contact High Mountain Helicopter Skiing, Box 173, Teton Village 83025; (307) 733-3274. Cost: $395.

Off-piste guides

Colorado. Copper Mountain Resort, Box 3001, Copper Mountain 80443; (303) 968-2882 or (800) 458-8386. Guided tours leave from the top of Copper Peak (elevation 12,444 feet) after a short hike from the Storm King lift. Cost (not including lift ticket): $18 one run, $30 two runs. A shuttle back to the base lifts is provided.

Crested Butte. Free guide service from the top of the resort's North Face lift heads to 260-acre "extreme limits" area. Free guided tours on the High Lift to 170 acres of backcountry skiing.

Montana. Bridger Bowl: contact Montana Powder Guides. Cost (not including lift ticket): $125 per guide full-day (groups up to four), plus $25 each additional person.

Utah. Ski Utah, 150 West 500 South, Salt Lake City 84171; (801) 534-1779. Backcountry tours link four or five ski areas. Cost: $95.

Wyoming. Jackson Hole (see above). Cost: guide rate is $190 for one skier, plus $30 each additional person; half-day guide rate is $100 to $110, plus $20 each additional person.