Members only: vacation ownership is Hawaii's invincible industry.

Time share (tim sher) n. a type of vacation-facility ownership that divides the use of a property into weekly intervals. Owners can purchase timeshares as: right-to-use, where the buyer does not have ownership interest but uses the unit for a pre-set amount of time; or fee-simple, where the

Sixty-eight resorts. About 4,600 units. And more than $276 million in annual sales. That is the size of Hawaii's vacation-ownership, or timeshare industry, according to the American Resort Development Association and other tourism-research groups. "We're bringing people to Hawaii in comparable numbers. That's the untold story," says Mitchell Imanaka, managing principal of law Firm Imanaka Kudo & Fujimoto. Each year, Hawaii hosts more than 400,000 vacation-ownership visitors. The number is expected to grow. In fact, vacation owners often have been compared to the more than approximately 420,000 MCI travelers (meetings, conventions and incentive trips) who come to Hawaii each year.

"Once people buy into vacation ownership, they've made an investment into the state," says Mark Wang, vice president of Hilton Grand Vacations Club. "The right mix of hotel and vacation ownership in a destination like Hawaii can be very beneficial during difficult times."

He's right. After the Sept. 11 terrorist attacks in 2001, vacation-ownership properties in Hawaii properties outperformed traditional resorts and hotels, according to a study by PKF Hawaii. The average occupancy at timeshare units in Hawaii that month dropped from 86.52 percent to 79.94 percent. The occupancy rate at resorts and hotels, on the other hand, plunged from 77.9 percent to 58.6 percent.

Ed Kinney, senior director for brand advertising and communications for Marriott vacation Club International, explains: "A high percentage of timeshare owners continue with their plans (in the event of difficult times). They either use their vacation, or lose it."

Growth in the vacation-ownership industry is expected to boom over the next decade, according to a study last year by the American Resort Development Association. In about five to 10 years, more than 3,000 new timeshare units will be added to Hawaii's existing inventory.