This talk gives an overview of the underwater acoustic environment in the Arctic. Sources of sound will be reviewed, including natural ambient noise (physical + biological) and man-made noise. Sound propagation characteristics will be discussed and examples from field studies will be presented. Features unique to the Arctic will be highlighted. Potential impacts of underwater noise on marine mammals will be summarized. Wild guesses will be made in an attempt to estimate how things might change in the future, particularly relating to climate change.