This is not a controversial interpretation or a speculative inference — it is a logical necessity.

Island habitation requires boats.

What kind of boats, and what specific capabilities those boats had, is a question that cannot be answered from the archaeological evidence currently available.

The physical remains of watercraft from 10,300 years ago do not survive in the archaeological record of the Northwest Coast — the combination of organic materials (wood, bark, skin), maritime exposure to UV, wave action, and biological fouling, and the passage of 10,000 years would be fatal to any boat not preserved in extremely unusual conditions.

But the logical inference from island habitation is not dependent on finding actual boats.