The beaches, tidal flats and islands of Setonakai National Park nurture a rich mix of coastal plants and marine life. Coastal areas are dotted with Japanese red pine and jolcham oak, and flowering plants like the yellow petaled Hibiscus hamabo and roundleaf chastetree.
Creatures such as the Japanese horseshoe crab and the finless porpoise inhabit the park's waters. The Suo-Oshima area is home to the world's largest colony of Japanese daisy coral and is a designated Marine Park.
The roundleaf chastetree (Vitex rotundifolia) is an evergreen shrub that grows in coastal areas. Its hardy leaves sustain it against heavy winds and dry conditions. From July to September, it produces bluish-purple flowers. In October, it yields small, brown fruits that are used as herbal medicine.
Koba-no-mitsuba tsutsuji (Rhododendron reticulatum) is a deciduous azalea. It puts out pinkish-purple blossoms between March and April in various parts of Setonaikai National Park.
The Japanese daisy coral (Alveopora japonica) is endemic to the temperate waters of East Asia. Tipped with tentacles, this species of coral has a striking resemblance to sea anemone. The Suo-Oshima area has the world's largest population of Japanese daisy coral.
The finless porpoise (Neophocaena phocaenoides) is a species of dolphin inhabiting Sendai Bay, Ise Bay and the Seto Inland Sea. Growing up to 2 meters long, it is typically smaller than a dolphin. It feeds on fish, shrimp, squid, cuttlefish and octopus.
