Philippe Cousteau Jr., the grandson of famed French oceanographer Jacques Cousteau, and ABC's Sam Champion dived into the gulf's oily water off the coast of Venice, La. for a report on "the damage you can't even see."

"This, critics say, is what BP does not want you to see," Champion says.

Cousteau, who was coated with oil during the dive, says: "This is a nightmare; this is a nightmare."

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