Stone Age settlement found under the sea in Denmark

Given human propensity to settle near bodies of water (exhibited even to this day), and the change in sea levels after the last ice age, the bulk of intra-ice age settlement artifacts are probably submerged within a relatively short distance from our existing coastlines. I would be personally interested in an effort to systematically investigate these areas.

This is probably especially an issue for early North American settlements if people crossing over during the ice age glacial maximum were traveling down the coasts right after coming over the Bering Land Bridge

Less than you'd think. The white sands footprints push things back far enough that virtually all coastal sites would have been destroyed by glaciers at the LGM. We're still trying to map out the specific details.