Civilization from the sea?

In his book Passage to Juneau: A Sea and Its Meanings, local author Jonathan Raban envisions the lifestyle of the people who first lived on Puget Sound. When Captain Cook and other European explorers arrived in the Northwest, they were enamored of the high impassable mountain ranges. The local tribes, however, showed no interest in the inhospitable altitudes.
Meanwhile, missionaries and other visitors were baffled by the easygoing schedule of the natives during canoe rides. Instead of pushing from point A to point B by the most direct or speedy route, locals paddled back and forth, talking to neighbors, exchanging things, or just catching up on the latest news.

The Europeans saw the sea as a wasteland to be crossed at great peril (perhaps because Europeans usually  could not swim). For Native tribes, however, the Sound was a fertile harvest, a marketplace, a town square - and a highway.
Spencer Wells, in The Journey of Man: A Genetic Odyssey, says that according to DNA evidence, the first  great migration of Homo sapiens from Africa followed the coast. Among the things that distinguished the more ingenious, adaptable Homo sapiens from Neanderthals were hallmarks of culture - like tattoos, and beads. In many languages, the word for "bead" is derived from the word for "pearl" or "coral" - rare things found at the bottom of the ocean. Carved beads have been found in caves that imitate shells - shells that were not plentiful there, because the sea was miles away. Usually whatever was depicted was something of great importance. Despite never seeing the shore, the sea held great value for them. Why would that be?

It may have been because the sea was the main trade route. Perhaps civilization's main impetus was not the wheel, but the boat. Why hack through miles of trees and underbrush, stagger over rocks and hills, when you can just float? Innovation, new ideas and foreign goods did not emerge from the woods - they arrived via the sea. Most modern cities are based on ports - the first primitive communities were probably founded on the same principle.

In The Wayfinders: Why Ancient Wisdom Matters in the Modern World, Wade Davis describes the Polynesian captains who could read the waves and the stars to find islands in the middle of the Pacific, without maps or compasses. Captain Cook's navigator from one island was able to step ashore, be identified by his adornment as a priest (including the tattoos and beads that some paleontologists think were one of the great achievements of human culture - the ability to connote social hierarchy to strangers) and was able to converse with the other islanders - surprising, considering that their islands were separated by miles and centuries. They were part of a cultural trade network that had existed for who knows how long?

Perhaps you've heard that many cultures have an oral tradition of "flood myths". There is also a strong tradition of creation myths in which a handful of sand grows to become an island, and then into the world.