The coastal route hypothesis has several things in its favor.

The Pacific kelp forest ecosystem — one of the most productive marine environments on Earth — extends from the northern Pacific southward along the North American coast and could have provided a reliable and abundant food base for coastal-adapted people moving south.

The coast itself, even when partially glaciated in the north, would have offered passage around the ice that blocked the interior.

And the timing of coastal deglaciation in the Pacific Northwest may have been earlier than the opening of the ice-free interior corridor.