pororocan.

1833 Philos. Trans. (Royal Soc.) 123 205 It occurs in the river of Amazons, at the junction of the Araway, having there a face of twelve or fifteen feet high, and producing a noise which may be heard at two leagues distance; it is called by the Indians of the neighbourhood Pororoca.

1884 Science 28 Nov. 490 The most powerful roots of the largest trees cannot withstand the pororóca.

1933 Sci. Monthly Apr. 351/1 The combat between the Atlantic tides and the discharge of the Amazon at its mouth results in the great Pororoca, or bore, a wall of water five to twelve feet high which rushes over the sandy shores and half-submerged islands at a speed of ten to fifteen miles per hour.

2001 F. Popcorn & A. Hanft Dict. Future 363 Surfers seeking greater challenges are taking on the pororoca, which..can reach heights of 15 feet.