My bet is on Monte Verde which is the oldest pre-clovis site so far. The linguists, archeologists, and geneticists have barely scratched the surface, and with so many tribes and massive terrain, their research is scant. However, I still love it all and can’t wait for this Beiringa theory to be thrown out along with the Polynesian flotsam theory.

And then…
I think whoever was here, struggled,
until the developement of Clovis weapons.
The weapons made big game hunting easier
and a population explosion then ensued.

Archeological and fossil records
only show what was common at the time.
They don’t show when types first appear;
they only show when types were common.

Bundles of reeds or skins stretched around a frame are probably earlier.

Lake Baikal’s warm springs were the refuge and source of the AmerIndian migrants, Innuit and Sinitic people. Beringia dammed the cold Arctic-Pacific ocean currents, so the coast was very moderate (warmer than today) while the inland was very harsh (the dam didn’t stop the air currents). These early Baikal folks used dugouts (which had originated in their tropical ancestors area where waters were filled with crocs and hippos), a later group (Innuit type) at Baikal hunted Baikal seals which made snow lodges on the ice (to keep their air-holes open for their pups and from which igloos derived), making sealskin ribbed boats followed the north coast to Alaska via the Anggara or Lena rivers from Baikal.
So there were two migrant waves from Baikal to the new world, one with dugouts ~20ka that moved slowly into America along the south coast of Beringea, (followed by a separate southward Sinitic migration to Asian coasts ~12ka) then one cold-adapted one with kayaks along the north Beringea coast to Greenland. The NaDene seem to have been part of the AmerIndian dugout group but were delayed (see Ket) before following eastward migrants. I think the original Baikal group were from the Amur river basin (chasing salmon inland following the Amur tectonic plate margin to Baikal) from Jomon/Ainu that had brought dugouts northeast from Java-India-Africa, the same group that split & settled Borneo 44ka, Timor 40ka (tuna bones in cave), Australia 42ka.

Yes, I believe diffused coast-hugging maritime culture(s)/technology(ies) would have greatly facilitated travel along the Pacific Rim. The peopling of Australia is sufficient evidence of the existence of such capabilities (although the ancestors of the coastal nomads would also have easily beachcombed their way out of Africa to the Asian bridgeheads to Australia without the need for boats).

And that’s the point. What would induce people to brave such a harsh environment as Beringia, even along the coasts, when the living was so much easier down south?