 The proposed use of boats adds a measure of flexibility to the chronology of coastal migration, because a continuous ice-free coast (16k-15k cal years BP) would no longer be required as migrants 
would have settled in coastal refugia during deglaciation of the coast.A coastal east Asian source population is integral to the marine migration hypothesis.A 2007 article in the "Journal of Island and Coastal Archaeology" proposed a "kelp highway hypothesis", a variant of coastal migration based on the exploitation of kelp forests along much of the Pacific Rim from Japan to Beringia, the Pacific Northwest, and California, and as far as the Andean Coast of South America.