Your keiki can take a picture with Apoha, the humongous 'o'opu fish, take part in natural resources-related arts and crafts activities, or play games that offer lessons on preventing water pollution. Interested? Head to Waikiki Aquarium's Earth Day celebration, the third annual Mauka to Makai Environmental Expo, 9 a.m.-2 p.m. today at the aquarium.

The expo will showcase the efforts of city, state and federal agencies to preserve and protect Hawai'i's environment, with an emphasis on the Islands' unique water resources — from mauka to makai. The first 500 families will receive a free native Hawaiian plant. In addition, the public is invited to cheer on the release of hatchery-raised aholehole, as well as 100 seahorses (bred at the Waikiki Aquarium) in the waters behind the aquarium within the Waikiki Marine Life Conservation District.

Admission to the festivities is free. Free parking and shuttle are available at Waikiki Elementary School. Details: 923-9741 or www.waquarium.org.