People capable of maritime or coastal travel could potentially have moved along those stretches and into the continental interior.

The challenge with the coastal route is evidence.

Most of the coastline of 23,000 years ago is now underwater, submerged beneath the sea level rise that accompanied the melting of the glaciers.

Sites that would have been on the coast at that time — exactly the sites that would provide the most direct evidence of coastal migration — are largely inaccessible to standard archaeological survey.

Underwater archaeology in the relevant depth ranges is technically demanding and expensive, and has so far produced limited evidence, though the search continues.

An alternative framework, sometimes called the “early entry” model, suggests that people may have arrived in the Americas well before 23,000 years ago — during a period when the glaciers were less extensive and the Bering land bridge was more accessible.