Sierra Club: Build a trail to Maunawili Falls, Saturday, Sunday and Aug. 24 and 25. Also on Sunday, the club cleans streams and stencils storm drains in Kaneohe. Call 538-6616.
Tantalus hike: Take the Central Loop Trail along the slopes of an ancient cinder cone and through forests of fruit trees with Betty Nakamura, Saturday. Four and a half miles, four and a half hours. Costs $5. Call the Hawai'i Nature Center at 955-0100.
"Rubber Boot" rodeo: Gates open 8 a.m. Saturday for slack roping, with rodeo action from noon Saturday and 11 a.m. Sunday, at Panaewa Equestrian Center, Hilo. Tickets $6 adults, free for children. Call 959-8932 or 961-4152, Big Island.
Waikiki Aquarium: Murder Mystery for families and adults, 7 to 9:30 p.m. Saturday. Costs $8 adults, $7 children. Call 923-9741.
Aiea Ballroom Dance Association: Monthly dance, 7 to 10 p.m. Saturday, Ala Wai Golf Course Palladium. Admission $3.
Ma'akua Gulch hike: Hike in Hau'ula, with Doug Klein of the Hawaiian Trail and Mountain Club, involves slippery rocks, lush tropical plants and a waterfall and pool, 8 a.m. Sunday. Six miles. Costs $2. Call 235-8330.
Frisbee fun: Demonstrations of tricks, skills and the game of Ultimate Frisbee, 10 a.m. to 2 p.m. Sunday, Bishop Museum. Free admission to mini clinic. Call 847-3511. Presented by Hawaii Ultimate League Association, Disc Golf in Paradise and the Island Jammers.
Contra dancing: Singles, families and beginners welcome, 7 to 10:30 p.m. Tuesday, Weaver Hall, Church of the Crossroads. Admission $5. Call 732-7540.
Free line dance lessons: 7 to 8:30 p.m. Tuesdays in August, Ka Elepulu Elementary, Kailua. Call 266-7815 or 235-7747.
Another group has free lessons 7 p.m. Thursdays in August at Windward Mall's Center Stage. Call 262-7441.
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.