Land elevation
Land elevation occurs in the northern locations where the ice from the last ice age, the Wisconsin glaciation, went over. This pressed down the land, and ever since the ice age ended, about 10,000 years ago, the land been rising. In Scandinavia, the land elevation in the northern parts is up to 1 centimeter per year, or a meter in 100 years, while in the southern parts only maybe 2-3 millimeters yearly.
Rocks and other things formerly located at the coast gradually become further away from the shore, while areas that were once ocean bottom come into visibility. The land elevation also leads to changes in the water structure when small islets become peninsulas and ocean bays become lakes.