At the peak of this high-water phase, most of Finland was under water, including present-day Helsinki at a depth of ; only southern Sweden was both free of ice and above the waterline. The Danish Islands were all connected west of the Strait of Oresund. Around 10,500 BP the climate became warmer, the ice retreated to the north of Mount Billingen, and the waters broke through central Sweden again, providing a second egress. Water level dropped to the sea level of that time.