is the second largest of the great bodies of water, covering 16.2 percent of the earth, and the Indian Ocean is third, covering 14.4 percent.

What, exactly, is an ocean? Oceans are vast bodies of saltwater that separate continents. Far to the west of us, after passing innumerable Pacific islands and remote atolls, the Pacific washes up on the shores of the continents of Asia and Australia. Although we commonly interchange the words “ocean” and “sea,” seas are in fact parts of oceans, but you must pass through some strait to reach them—the Strait of Gibraltar from the Atlantic Ocean to the Mediterranean Sea being one example. Or, farther south along the course we were pursuing, at the tip of Baja California lies the entrance to the Sea of Cortez.

For roughly 5,000 years, people have ventured into the vastness of the oceans and seas, seeking food, trade, a new place to live—or just yielding to the urge to explore the unknown. As long as 4,500 years ago, the ancient Egyptians built vessels that traversed the Mediterranean Sea to places as distant as Lebanon to bring back lumber and other trade goods. And, from the earliest written records, the dangers inherent in the sea—storms and giant waves that crushed frail vessels—are evident.

In The Odyssey, Homer (eighth century B.C.) describes how Odysseus, after offending Poseidon, god of the seas, witnesses his raft destroyed by a mighty wave:4

With that he rammed the clouds together—both hands clutching his trident—churned the waves into chaos, whipping all the gales from every quarter, shrouding over in thunderheads the earth and sea at once—and night swept down from the sky—East and South winds clashed and the raging West and North, sprung from the heavens, roiled heaving breakers up—

…At that a massive wave came crashing down on his head, a terrific onslaught spinning his craft round and round—he was thrown clear of the decks—

The story has a happy ending, however, because Ino, a sea nymph, takes pity on Odysseus and gives him her veil as a life jacket. He strips off his clothes and manages to swim to shore as his raft is lost. Unfortunately, the outcome for many other victims of ships struck by giant waves is not as happy; numerous ships have disappeared leaving no survivors, only pieces of floating debris to mark their demise.

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