Skiing’s a growing industry, and at the start of every season, there’s something new to look forward to on Colorado’s slopes. This year the big news has to do with a mountain activity that isn’t skiing or snowboarding — mountain coasters. After you try it, you might decide it’s your new rest-day activity. But there’s plenty to celebrate if you’re a skier, too, including a terrain expansion at Arapahoe Basin, new high-speed lifts and more. What’s new in ski country for the 2017-18 season Mountain coasters: Snowmass, Copper Mountain, Purgatory and Steamboat all will open new mountain coasters — gravity-driven roller coasters elevated 4 to 40 feet off the ground.