We travel the ocean this issue, and as befits a place so vast, we have taken several different routes in our explorations.

But perhaps all of our stories come down to this: How do we understand the ocean as part of not just our biological environment but also our "moral universe"? This is roughly the question posed by Hal Whitehead, one of the world's leading experts on sperm whales and their culture, the socially learned behavior and language they pass down from generation to generation. As reported by author Peter Canby, Whitehead's pioneering work has further established the species as one of the planet's most highly evolved animals. And yet as we expand our knowledge about whales, they have come under increasing assault: from U.S. naval ships blasting sonar during military exercises, from enormous commercial fleets whose loud engines and seismic explosions -- designed to pry new sources of gas and oil from the sea-bed -- are driving whales, dolphins, and other marine mammals to the most wretched deaths. Beached whales have been found bleeding profusely from the eyes and ears. Others suffer from symptoms similar to those of the bends, an often fatal condition that afflicts divers when they rise too quickly to the sea's surface, as whales might do in response to explosive assaults on their exquisitely sensitive auditory system, which is essential for navigation, mating, and ultimately survival.

A mind-boggling array of human activities takes place in the oceans. We hunt ravenously for our food in it, we dump all manner of our waste in it -- from raw sewage to petrochemicals to carbon dioxide released from cars and factories -- and we do all of this on a scale so massive that the watery world we once thought too immense to register our puny impact has begun finally to falter and fall ill.

Ninety percent of international trade still travels by sea, in immense, hulking freighters that run on the lowest-grade, most polluting form of diesel fuel. In the ports of California's San Pedro Bay, which are the largest in the United States, thousands of container ships pull into harbor every year, belching dark smoke and choking the fami-lies that find themselves choicelessly living next door. Author Wade Graham points out that we are sometimes tempted to regard the New Economy as cleaner than the old one, streamlined and practically shimmering with efficiency. But the reality is grittier and more lethal. "We click off our wishes on Web sites," writes Graham, "setting in motion diesel engines by the tens of thousands: trucks, loaders, cranes, and locomotives, armadas of little smokestacks toiling to deliver us the goods."

Which leads me, again via sea currents, to Elizabeth Kolbert's essay on the pioneering author and environmentalist Rachel Carson, whose centennial comes this spring. The ocean, Kolbert reminds us, was Carson's first love and creative inspiration. She wrote three best-selling works about the ocean before her groundbreaking Silent Spring was published in 1962. In that work, she, too, placed our relationship to the natural world in a moral context: "The question," Carson wrote, "is whether any civilization can wage relentless war on life without destroying itself, and without losing the right to be called civilized." Grasping this truth could yield an ocean of different possibilities.

Douglas S. Barasch