"A lack of coastal irregularities, " such as substantial barrier islands or hills, and the Gulf of Mexico's flat bottom make southern Louisiana "ideal for wave damage, " according to the National Weather Service Web site.
Sea levels were 150 feet lower then, because the cold had locked up so much moisture in northern ice-caps, so not only were most Indonesian islands linked by land, but the Persian Gulf was dry and, crucially, the southern end of the Red Sea was a narrow strait.