The mawa yuxibu are the spirit-masters of the water's edge, the powerful yuxin who own the riverbanks, lakes and deep pools where the world's spirit-charge runs highest. In Cashinahua reckoning the landscape is unevenly animate, and these watery places are among the most dangerous, thick with agency that can act upon a careless human. To fish, bathe or travel there without care is to risk an encounter in which the water-master seizes a person's wandering soul, and the resulting sickness can be lifted only by a shaman who knows how to treat with such beings. They belong to the same order as the anaconda people of the deep waters, and share in the ambivalence of all Cashinahua water-spirits, at once the source of vision and design and a standing threat to the living.