Cate is a character who first appears in Act IV. She is the captain of the Mucky Mammoth and helps transport the characters down the Echo River. Cate knows a great deal about mushrooms and their medicinal properties, having become interested in alternative medicine following a chance encounter outside of a hospital. She remarks that mushrooms "escape your erudition" and that, because of their elusive nature, they must be hunted rather than simply found or picked.

Cate is also a doula, assisting women on the surface in childbirth.