Here’s the setting for my second book: Beringia circa 10,000 BC.
As you can see, at this time the sea levels were lower (coastlines are a guess). Volcanoes were active in what is now the Kamchatka Peninsula.
The area that is now the Bering Strait is believed to have been a vast plain that somehow, despite being so far North, supported a great variety of game, including different varieties of mammoth.
Meanwhile, weirdly, North America was still covered in ice sheets. No one knows why this should be, but here is a guess. Anyway, the ice sheets were beginning to melt, creating an ice-free corridor down into the Americas. When exactly this corridor became passable is up for debate. There may also have been a coastal way to access North America (not shown on this map). Meanwhile, there could also have been people migrating to America from Africa via the Atlantic, and from Asia via Polynesia.
The corridor could also have been the route that Gigantopithecus took to get to America.
Late in the book, my characters discover mountains of ice. The ice is south of them and lies between them and the sea. They are just as confused by this as you are.