"Mauka to Makai," an environmental expo set for 9 to 2 p.m. Saturday at Waikīkī Aquarium, offers family-friendly activities and hands-on educational displays. The free green event will showcase more than 20 city, state and federal agencies that work to preserve and protect Hawai'i's environment, with an emphasis on Hawai'i's water resources.

Highlights for kids: A release of kona kampachi and seahorses into Wakīkī conservation waters, water pollution prevention games and activity books, natural-resource arts and crafts and picture-taking with water quality mascot 'Apoha the O'opu. The first 500 families through the door will get a native plant in celebration of the aquarium's new Hawaiian Native Plant exhibit.

Free parking and a shuttle are available at Waikīkī Elementary School; 923-9741, www.waquarium.org.

LYON ARBORETUM

HERBS, TREES, FLOWERS, MORE FOR SALE

Lyon Arboretum is greeting spring with a horticultural sale, 9 a.m. to 2 p.m. Saturday at Blaisdell Exhibition Hall, featuring herbs, exotic fruit trees, flowers and tropical plants, native Hawaiian plants and more.

Plant doctors will be available to answer questions, there will be activities for keiki and volunteers from the arboretum's Hui Hana Hawai'i will be selling fresh haku lei, jams and jellies and crafts.

Admission, $2, benefits the arboretum, a 193.5-acre rainforest botanical garden administered by the University of Hawai'i-Mānoa; 988-0456, www.hawaii.edu/lyonarboretum.

— Maureen O'Connell