Whether you want to pick up trash at a beach, learn how to make a rain barrel, cultivate native plants or enjoy eco-conscious art and music, opportunities abound to be green this month.

The first Earth Day, founded by Gaylord Nelson, then a U.S. senator from Wisconsin, occurred in 1970, and it has become a marketing as well as Hallmark opportunity over the decades.

Earth Hour—which called for a voluntary lights-out to conserve energy—already occurred at 8:30 p.m. around the globe on March 27.

Although Earth Day is April 22, there are events through the month. Most of the events are hands-on and free, so here's your chance to be green.

» B.E.A.C.H. Student Art Display: The Beach Environmental Awareness Campaign Hawaii displays that aim to educate the public about the effects of marine debris show at the state Capitol, Hawaii State Library, ING Direct Cafe and public libraries in Ewa Beach, McCully-Moiliili, Liliha, Waianae, Waipahu, Kailua and Kaneohe as well as 12 different schools. Free. For more information, visit www.b-e-a-c-h.org.

» Duke's Waikiki Reef and Ocean Expo: 11 a.m. to 1 p.m. today at Duke's Waikiki, Outrigger Waikiki Hotel. Features exhibits on ecosystem management, box jellyfish, invasive algae, coral reefs and water safety. Free. Call 922-2268.

» Mauka to Makai Environmental Expo: 9 a.m. to 2 p.m. tomorrow, at the Waikiki Aquarium. Includes water pollution prevention games, natural resource arts and crafts and storytelling about Hawaii's environment. Release of 100 sea horses and hatchery-raised aholehole from Anuenue Fisheries are among the day's festivities. First 500 families receive a free native plant. Free. Call 923-9741.

» Earth Day in Kailua: 10 a.m. to 3 p.m. tomorrow at Kawainui Neighborhood Park. Hui o Ko'olaupoko hosts its second annual Earth Day, offering educational exhibits, a hands-on watershed model and wetland bird guessing game. The Board of Water Supply hosts a rain barrel construction workshop from 10:30 to 11:30 a.m. (Cost is $5 plus $30 for barrel construction materials.) Hui Ku Maoli Ola hosts a free native plant workshop and tour of Kaha Garden from 12:30 to 1:30 p.m. Reservations required for workshops; call 381-7202 or visit www.hsblinks.com/29b.

» Pearl Harbor Bike Path Cleanup: 8:30 to 11 a.m. April 17; check in by 8 a.m. at either Blaisdell Park or Kapakahi Stream. Visit www.cleanwaterhonolulu.com.

» Earth Day Festival: 9 a.m. to 2 p.m. April 22 at Kapiolani Community College. Outdoor festival offers food, fun and education. Call 734-9000.

» Adopt-a-Beach Cleanup: Noon April 24 at Chun's Reef. Bring a hat, sunscreen and beach shoes; volunteers are provided with trash bags, water and gloves. Visit www.adoptabeachhawaii.com.

» Kokua Festival: 4:30 p.m. April 23 and 24 at the Waikiki Shell. Benefit concert for the Kokua Hawaii Foundation featuring Jack Johnson, Ziggy Marley, Taj Mahal, Jake Shimabukuro and Anuhea. Sold out; visit www.kokuafestival.com.

» ”;Build Green”; Screening: 5:30 p.m. April 27 at the Honolulu Design Center. The Honolulu architecture community presents “;Build Green,”; a 44-minute video documentary hosted by David Suzuki. No-host cocktails will be followed by a video presentation at 6 p.m. and panel from 6:45 to 7:30 p.m. Free; register at www.aiahonolulu.org or call 545-4242.