Cranfillia fluviatilis, synonym Blechnum fluviatile, is a fern known in the Māori language as kiwikiwi.

A herbaceous plant, C. fluviatilis is a "hard fern" of the genus Cranfillia in the family Blechnaceae.

[3] As the parent plant ages it develops a short trunk central to a surrounding colony.

Example understory flora associates in the mixed broadleaf/podocarp forests of Rakiura include Austroblechnum durum.

[5] It was collected by William Colenso in December 1841, at the precise locality of woods near Poverty Bay in the North Island.