But watercraft alone were not sufficient.

The crossing also required navigation knowledge: the ability to determine a heading and maintain it, the ability to read weather and sea conditions, the ability to judge when a crossing was feasible and when it was not.

These are cognitive and experiential skills, not just material ones.

A person with a raft but no navigation knowledge might not survive an attempt to cross the Santa Barbara Channel; the currents, the winds, and the possible fog that characterize the channel in certain seasons could drive a vessel off course or delay a crossing to the point of disaster.

Navigation in the terminal Pleistocene Santa Barbara Channel — without compasses, without charts, without any of the navigation instruments developed in later centuries — would have relied on the same techniques that maritime peoples around the world developed before modern navigation aids: the position of the sun, the stars, the direction of prevailing winds, the shape of waves, the flight patterns of birds, and the sight of the island itself on clear days.