[tzs]

One point in favor of a water route is you can carry a lot more stuff that way. Most of the migrations into the Americas were before animals other than perhaps dogs were domesticated and before the wheel was invented.

So anything you wanted to bring with you on a land route had to be carried by humans, dogs, or pulled on sleds by humans or dogs.

On a water route you could tow another boat or raft behind full of your stuff. (Rope was invented long before any migration to the Americas).