The sudden release of five million barrels of oil, enormous quantities of methane and two million gallons of toxic dispersants into an already greatly stressed Gulf of Mexico will permanently alter the nature of the area.

Since the middle of the 20th century, more has been learnt about the ocean than during all preceding human history; at the same time, more has been lost.

I find the lure of the unknown irresistible.

Ten percent of the big fish still remain. There are still some blue whales. There are still some krill in Antarctica. There are a few oysters in Chesapeake Bay. Half the coral reefs are still in pretty good shape, a jeweled belt around the middle of the planet. There's still time, but not a lot, to turn things around.

Never before have we known what we know.

I've spent thousands of hours under water. And even in the deepest dive I have ever made, 2.5 miles (about 4 kilometers) down, I saw trash and other tangible evidence of our presence.

Even our rules and regulations, our laws, our policies, favor the destructive nature of taking too much from the ocean and using techniques that are horribly destructive. We know they don't work. We know it's not sustainable.