I've seen illustrated maps of Doggerland at the glacial maximum, when sea levels were about minimum. It was a huge land mass with all sorts of rivers and (probably) lakes and marshes.
Same for the west coast of Canada. Sea levels were 100m below the present. Beringia was a colonized land mass. The interior glaciers forced the human population to the coast. The tide went out twice a day, exposing a feast of intertidal life. Very difficult to starve on the coast here.
Heiltsuk oral historians can pinpoint the location of ice age villages. One recently investigated was exactly where they said it was and some 14,500 years in age. Their cultural geographic heritage is secure. I met a "story-keeper" this year. I had no idea that it was a full-time, specific tribal job for someone selected for aptitude.
In river estuaries, salmon are trapped and harvested in their hundreds and thousands in big stone weirs. Parks Canada scuba divers have explored the estuaries out to 70' depths to see identical salmon weirs, abandoned with post-glacial rising sea levels.
Some modern geologists point to the island archipelago of Haida Gwaii and claim that the glacial melt was so fast that the village you were born in would be submerged by the time you died.