Mount Pensacola was an active volcano in the mouth of the Bay of Mexico, off the coast of northern Terranova. Its eruptions gradually expanded the coastline over time.
The rocks shot by the erupting volcano got far out to sea, far beyond the range of human-made coast artillery, and constitutied a hazard to shipping. In 1793, the Black Prince was sunk by a boulder, "as big as cow" thrown by Mount Pensacola. Since then, ships gave the mount a wide berth in times of eruption.
Mount Pensacola erupted again in 1833. Ten years later, when John James Audubon sailed by, the mount was quiet - though a new eruption was expected sooner or later.