Aspen Snowmass Ski Resort, in Colorado, offers more than 5,200 acres across four mountains, two of them dedicated to advanced skiers. Snowmass is 32-percent Double Black Diamond (steep and/or dangerous terrain icons, to the uninformed). Aspen Mountain offers even more thrills, with 26-percent Black Diamond runs and another 26-percent Double Diamond runs. The mountain, nicknamed Ajax, is renowned for its precipitous slopes and moguls (read "big bumps", for the uninitiated) that can send the unwary or reckless ski aficionado flying into white space.

Aspen has 76 trails and 8 lifts, with no beginner slopes and half the terrain given to intermediate runs. The remainder is about equally divided between advanced skiers and experts. Experts will love the challenge of double-black slopes and woodland terrain. For a real rush, try the Go-Go-Gully or the Highland Bowl, pitched at roughly 48 degrees (90 degrees is a right angle, for expert skiers who don't do math).

Killington Ski Resort, located in Vermont, is a superb resort for the advanced skier. Almost half of the terrain is devoted to advanced trails, including the Double-Black-Diamond rated "The Outer Limits" which has enough moguls to make even expert skiers achieve flight. Other terrain includes woodland, or glade, skiing and steep terrain. Killington has 12 Double Black Diamond trails and 18 Black Diamond runs. In all, 200 trails connect seven mountains via 33 chairlifts. Killington has the longest skiing season in the Northeast U.S. (typically November through April), an average annual snowfall of 250 inches, and 70-percent snowmaking capacity. Lessons are available without advance reservation at the Perfect Turn Ski School.

Mad River Glen, in Vermont, features a mountain that is only open to skiers; no snowboarding or tubing allowed. The Glen is not well known, but its motto, "Ski It If You Can" indicates the level of difficulty. Most of its snow is Nature-made, providing natural moguls. Narrow, wooded trails and 45 advanced trails offer the ultimate in skiing challenge. Five lifts provide adequate coverage to the 800 acres of skiing. For Eastenders, the Glen is 3 hours from Boston and just a little further from New York.

Winter Park Ski Resort in Colorado has a variety of skill-level trails, but the most difficult ones comprise more than half the terrain. One peak, the Mary Jane, starts at 12,000 feet and runs four miles down the mountain with a 2,600-foot descent. More than half the trails on Mary Jane are listed as difficult. The Pansenne Bowl starts at a similar elevation and drops 1,700 feet in five miles. The truly expert trails are located on the Vasquez Cirque, with three-quarters of these listed as advanced and the balance for expert skiers only.

Breckenridge Ski Resort is also located in Colorado. Half of the trails are rated as advanced or expert, with around 23 trails in the Double Black Diamond class, featuring snow bowls, woodland terrain and backcountry wilderness. Breckenridge also has a terrain park for advanced extreme skiers - the kind who have learned to fly on a pair of skis. With over 100 trails and some 29 lifts, including the highest chairlift in N. America, Breckenridge will delight skiers who have mastered more than a parallel stop. Breckenridge also has a ski school, and its historic downtown offers the non-skier and skier alike endless shopping, dining and nightlife opportunities.

Other mature-rated ski resorts include Mammoth Mountain in California, with 150 trails and one of the best back-country ski routes in N. America. Whiteface Ski Resort, in Lake Placid, New York, offers the highest vertical drop in the East (3,340 feet), and an area known as "The Slides", which are Double Black Diamond runs without snowmaking or grooming that form steep chutes, or gullies. If you are less than expert, think twice before attempting The Slides.