Ski resorts and water parks are quite profitable during the winter and summer, respectively.

But few people want to try skiing without snow or water slides slicked with ice. So what’s a seasonal industry to do in the off season? Become a year-round attraction.

Whitefish Mountain Resort had a remarkable summer this year, which president Dan Graves attributes to new and improved summer activities.

The mountain now boasts an alpine slide, zip lines, lift service, hiking and biking trails and a walking course high above the ground.

“Whenever I chose a product or an activity, I like to look at tried-and-true concepts that have a track record,” said Graves. “When you plan the activity, put a good, conservative estimate of the business volume. We estimate at a conservative level to justify the investment.”

Graves said summer numbers “surprised the heck” out of the resort staff.

Guests on the mountain took more than 40,000 lift rides, a 43 percent increase over 2008’s numbers. The alpine slide was ridden nearly 43,000 times, representing more than a 100 percent increase from the year before.

The bike trails, Summit and Runaway Train, had more than 2,000 cyclists, 66 percent more than estimated. Runaway Train, the advanced-level course, is a new feature, and the resort plans to add a beginner-level track to be named Gravy Train.

“We knew we had to do something,” Graves said of the bike trails that formerly consisted of just Summit, which is too difficult for beginners and too easy for experts. “It was like having a ski resort with one blue trail.”

“The response has been that [Runaway Train] is very well designed,” said Donnie Clapp, public relations manager of the resort. “It flows well.”

The zip line tour, in its first year, carried nearly 10,000 riders. The tour consists of four different stages, each with three-fourths of an inch parallel wires (stout enough to support a small lift) so that friends and family members may ride beside each other.

“It’s a new enough activity that a lot of people have never done it before,” Graves said. “It’s a thrill experience without a lot of skill needed.”

In some places on the tour, it’s possible to zip along at a brisk 30 mph. To help guests feel comfortable, the harnesses are similar to those used for paragliding. The harnesses don’t allow riders to spin and they have more than one point to tie in.

“It’s over-engineering to show people this is a pretty safe opportunity,” Graves said of the attraction that the resort began planning in summer 2008.

Graves said the resort will add two more stages of the zip line tour that will lengthen the tour to more than two and a half hours. The new lines will be 1,600 and 1,800 feet long and the fifth stage will suspend riders almost 300 feet above the ground.

For those seeking a bit less of a thrill, Grave recommends “Walk in the Treetops,” a guided tour of the forest from an elevated boardwalk through the treetop canopy that has entertained guests since 2002.

“It’s a good alternative to zip lines,” Graves said. “A little bit less thrilling or scary, but certainly more exhilarating than you might think.”

Reporter K.J. Hascall may be reached at 758-4439 or by e-mail at kjhascall@dailyinterlake.com