Already back in 1835, surveyor Joseph Hamel noted the abundance of fish, including trout, salmon, carp, and whitefish.

Several Governors General of Canada, including The Marquess of Lansdowne and Lord Stanley, had summer homes along this river.

Almost its entire course is protected in the Cascapedia River Wildlife Reserve (réserve faunique de la Rivière-Cascapédia), established in 1982.

Its name comes from the Mi'kmaq word gesgapegiag, meaning "strong current" or "large river".

Because its source is the Chic Choc Mountains that are largely made up of soluble limestone, its waters are rich in carbonates and low in sulfates and chlorides, with a higher conductivity and pH level than typical water of the Canadian Shield.