Today marks the one-year anniversary of the BP Deepwater Horizon oil spill in the Gulf of Mexico.

"I think the environmental impact of this disaster is likely to be very, very modest," claimed BP Chief Executive Tony Hayward following last year's Deepwater Horizon disaster on April 20.

But in fact, "The spill here in the Gulf of Mexico is the worst environmental disaster in the history of our continent."

Greenpeace has been working with independent scientists from universities around the country to find out what has really happened to the oil, and what the long term impacts will be on this critical, fragile ecosystem. Stay tuned.