The Asmat lowlands are a maze of mangrove, tidal swamp, freshwater swamp, and rainforest. Birdlife is rich, with parrots, lorikeets, birds-of-paradise, and many species that make you work hard for a glimpse.
This is not a signed nature park with easy trails. You need boat transport, local knowledge, and patience, and you should expect heat, mud, mosquitoes, and sudden rain.