[GSlob]

To arrive by water one would need a serious craft - either large rafts ("Kon-Tiki" type) or primitive ships. Such craft being sizable, the remnants of at least a few would be likely to survive either physically [like viking longboats], or at least in the lore. What is the age of the oldest boat/raft remnant ever found around the Americas?

[RightWhale]

Of the most feared warship in history, the Athenian trireme, not one survives.

[expat_panama]

Land/water travel does not have to be either/or.   Pop-science news blurbs fly all over the place but the consensus stays pretty constant.  Land routes are shown on simple maps because it's well, simpler.  Even population shift maps don't leave much room for differentiation between travel modes.  My favorite rendering of the consensus (CLICK! IT'S A MUST SEE) gets into more detail of the interplay between different routes.  It's supplementary info, not a contradiction.

The controversy is over dates.  Then it becomes a fuss between adults who do this for a living and a bunch of 'me first' clowns and their press agents.

[doc30]

Back then, the continents were connected and sea travel may have been along the coast by water rather than hiking across land. Inuit traveled between the Aleutian islands and the mainland by kayak.

[Fraxinus]

I disagree, it depends upon where your starting point is compared to your destination, most (probably all) of the water hazards on the coastal route from the Yellow Sea could be easily traversed in a day in a curragh (hide boat). Any large canoes or curraghs that sank are now under ~150ft or more of water and sediment.

[Captain Rhino]

It is unlikely any boat constructed of organic materials and using the technology of the time could survive so long except by an extraordinary set of circumstances.

While there have been discoveries of the remains of sizable wooden ships in the waters of the Mediterranean and in the deserts of Egypt, the oldest (probably the Cheops pyramid boats at @2000 BC) are nowhere near the 50,000 years before the present date suggested in this article.

Since the boats in the two coast migration theory would be entirely organic and the biological zones they would be lost/abandoned in are particularly active, it is unlikely that they survived.

There is another factor to consider. Genetic testing of various Native Americans seem to argue they are all descended from a relative handful of migrating families. Given the amount of time that has passed, only a few would be needed to produce so many descendants. Whether you like the overland migration theory or the bi-coastal water migration theory, there were probably not a lot of people in the original groups. And that means not too many organic artifacts entered into the fossil record. After 500 centuries in the ground or water or somewhere in between, what's likely to be left except stone tools and other similarly hard objects?

[blam]

Iberia, Not Siberia?

[blam]

Immigrants From The Other Side (Clovis Is Solutrean?)

[Renfield]

Remember, 12,000 years ago, sea level was 300+ feet lower than it is today. The "Grand Banks" off Newfoundland, where cod-fishing existed until recently, was above water then. The coastline from Cape Hatteras to central Florida was 45-70 miles east of the present shoreline. The Chesapeake Bay was a forested river valley. Any boats...and I'm sure there were many....would have been ditched along the coastline, which is now under 300+ feet of ocean. If any still exist (remember, marine worms eat wood), they would be pretty hard to locate.

[FastCoyote]

"To arrive by water one would need a serious craft - either large rafts ("Kon-Tiki" type) or primitive ships. Such craft being sizable, the remnants of at least a few would be likely to survive either physically [like viking longboats], or at least in the lore. What is the age of the oldest boat/raft remnant ever found around the Americas?"

Eskimo kayak and larger skinned craft are seaworthy but not very preservable. Coastal craft wouldn't have to be large at all, especially when the ice sheet was larger.