The waters of Ripliancum are a body of water mentioned briefly in the Book of Mormon. In the Book of Ether the waters were a battleground during the Jaredites final war between the armies of Coriantumr and Shiz. Coriantumr, seeing that his armies were about to fall, fled to the the waters and pitched his tents. Shiz and his army did also, until they came together in a battle so fierce that Coriantumr was injured and fainted from loss of blood. The battles continued and moved elsewhere until all were killed except Coriantumr.
The location of the body of water is not known, though it is interpreted in the scriptures as being large or to exceed all.