Pinball Wizard Contest: Players 18 and older may register at 6 p.m. Saturday at the Pier Bar, Aloha Tower Marketplace. The first 50 entrants will receive a free "Tommy" CD; the grand prize is a dinner theater package for the premiere of the rock opera at Manoa Valley Theatre. Finals will be Sept. 7.
Kuolani-Waianu hike: Dick Davis of the Hawaiian Trail and Mountain Club leads a pleasant five-mile "ramble" across streams, roads and trails, 8 a.m. Sunday. Costs $2. Call 247-3922.
Tai chi chuan: Alex Dong teaches the Chinese art of meditation with movement, 4:30 p.m. Mondays and Thursdays in September, beginning Sept. 5, Queen's Medical Center. Costs $35. Call 547-4780.
"Run What You Brung" contest: Rising Sun Hobbies offers cash prizes for the best models of aircraft, ships, trucks, autos and armor and dioramas, Sept. 21. Customers will decide the "Best in Show" prize of $500; grand prize is $250; and each category will have first-, second- and third-place prizes.
Kits must have been purchased on or after July 25; receipt must be turned in with entry form. For rules and entry form, see Rising Sun, 835 Keeaumoku St., Suite 201. Call 942-2851.
Sports Acrobatics Hawaii: Hawaii Highflyers Trampoline Club for adults and kids, 4 and 5 p.m. Mondays and Wednesdays, McCully Recreation Center. Call Karl Vorwerk at 949-3747.
Waikiki Acrobatic Troupe meets 4 p.m. Sundays at the beach across Kapiolani Park Bandstand; free workout at UH Studio Four 8 p.m. Wednesdays. Call Don Heafner at 536-7205.
Learn to swim: Children practice Saturday mornings at Ala Moana Beach; adults, Monday, Wednesday and Thursday evenings. Free. Call the American Red Cross, 734-2101 ext. 123 or 124.
Free hike to Diamond Head: Meet the Clean Air Team at the Honolulu Zoo entrance, 9 a.m. Saturdays. Three miles to the top. Call 948-3299.
Philippine folk dancing: 2:30 to 4:30 p.m. Saturdays, Lanakila Gym. Free. Call 455-9963.
Hash House Harriers: Social runs with Aloha group 3 p.m. Saturdays; call 948-AHHH (948-2444). Or Honolulu group 5:30 p.m. Tuesdays; call 948-HASH (948-4274).
Hawaii Israeli Recreational Dance: Noon to 3 p.m. Sundays, Ala Wai Ballroom. Costs $3.50. Call 623-3603.
Honolulu Marathon Clinic: Free training runs with Jack Scaff and staff, 7:30 a.m. Sundays, Kapiolani Park Bandstand. Call Norm at 247-4957. No meetings on three-day weekends.
Ikebana classes Lillian Koide teaches flower arrangement 9 a.m. to noon Wednesdays at the Japanese Cultural Center. Tuition $30 per month plus supplies. Call 537-5765 evenings.
International folk dancing: Includes Bulgarian, Greek, Rumanian and Israeli dances, 7 to 9:15 p.m. Sundays, Makiki District Park. Donation. Call 923-0362.
Line dancing: 9:30 to 11 a.m. Tuesdays, Waikiki Community Center. Costs $3. Call 923-1802.
Scandinavian dancing: 7 to 9 p.m. Wednesdays, Ala Wai Golf Course Clubhouse. Free. Call 922-0793 or 955-2577.
Pali Twirlers square dance: 7:30 to 9:30 p.m. Thursdays, Yacht Club Terrace. Call 254-2333.
Honolulu Zoo: The zoo opens at 8 a.m. on the first and third Wednesdays of the month. General admission $6; $2 with Yum Yum Tree senior card. First Wednesdays feature a botanical tour at 8:45 a.m. for $2 more. Third Wednesdays, tai chi practice begins 8 a.m. Call 971-7174.
Nature Conservancy hikes: Two guided hikes a month to Honouliuli Preserve, home to more than 45 rare native plants and animals. Donation. Call 537-4508.