The Clovis-First model says humans reached the Americas by trekking overland, but others propose the earliest travelers arrived by sea, paddling small boats along the coast, from East Asia to southern Beringia and down the western coast of the Americas. Scientists first began thinking about this route in the late 1970s, when they started examining geologic and pollen records to reconstruct ancient environments along Canada's western coast. Instead of the entire northwestern coast laying under thick ice, analyses of coastal bogs showed that a coniferous forest thrived on Washington's Olympic Peninsula 13,000 years ago, and that other green refuges dotted the coast. Early humans camping in these spots would have found plenty of shellfish, salmon, waterfowl and caribou or other land animals grazing in the larger spots.
In fact, it is now known that much of the British Columbian coast was ice free at least 16,000 years ago. Although they haven't found any preserved boats, they were known to humans at least 45,000 years ago when humans island-hopped from Asia to Australia. Still, finding campsites of these exploring mariners are hard to find. This is because as the ice sheets melted, the sea level rose, drowning ancient coastlines under meters of water. However, in March 2011, evidence of early seafarers was found on Santa Rosa Island, just off the southern California coast. Nearly 12,000 years ago, Paleo-American sailors crossed 10 kilometers of open water to Santa Rosa, which would have required a boat. Bird bones and charcoal found at the site were dated to 11,800 years ago.
These travelers had hunted Canada geese and cormorants as well as pinnipeds (seals and sea lions). They also left behind distinctive technology, more than 50 dainty stemmed points that may have been part of darts used for hunting. Their design seemed very unlike the long, furrowed and sturdy-looking Clovis spearpoints. Very similar stemmed points were found scattered around the northern rim of the Pacific Ocean. The earliest came from the Korean peninsula, Japan and the Russian Far East, and were dated to around 15,000 years ago. Stemmed points found in Oregon were dated at 14,000 years old, and 12,000-year-old points were found on the Channel Islands, in Baja California and along coastal South America.
Even so, explorers of this rich coastal world were unlikely to have raced southward. They may have moved just a kilometer or so a year. They were moving into unpopulated lands, and had to maintain connections with people behind them in order to have marriage partners available.
https://www.scientificamerican.com/article/the-first-americans/#:~:text=For%20decades%20archaeologists%20thought%20the,thousands%20of%20years%20before%20that.