Deepwater Horizon fire

In September, Deepwater Horizon, an oil rig owned by Transocean and leased to BP, drilled the deepest oil well in history at a vertical depth of 35,050 feet. On April 20, an explosion left 11 crew members dead and unleashed a torrent of oil into the Gulf of Mexico that has since added up to many millions of gallons.

Since the explosion, BP and U.S. government agencies been struggling to contain and clean up the massive flow. Meanwhile, oil continues to gush. It has already devastated stretches of the Louisiana coast, threatening wildlife and livelihoods.

On Friday, BP CEO Tony Hayward acknowledged in an interview with CNN that the situation has become an "environmental crisis and catastrophe." Also on Friday, the company said that it is continuing with its "top kill" effort to try to stem the flow of oil, and Hayward said, "I think it's probably 48 hours before we'll have a conclusive view of this."

In this slideshow, CNET takes a look at efforts over the past five weeks to contain the disaster. In addition to the overall work to stop the flow itself, other efforts have included burning off oil, using chemical dispersants, and building booms and levees.

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Photo by: U.S. Coast Guard / Caption by:

Oil spill

Here is an aerial image of oil on the Gulf's surface, taken from a U.S. Coast Guard aircraft in early May.

On Thursday, the U.S. Geological Survey estimated the well has spewed about 500,000 to 1 million gallons each day--greater than a previous estimate of 210,000 gallons a day.

If the estimates are accurate, even the most conservative figures would mean this disaster is worse than the 1989 Exxon Valdez spill in Alaska. The Valdez spilled 11 million gallons into Prince William Sound.

BP said Friday that it now estimates the total cost of the response to the Deepwater Horizon disaster at $930 million.

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Photo by: Spc. 1st Class Michael B. Watkins / Caption by:

Cofferdam set on ship

On May 5, a containment cofferdam is hoisted onto the deck of a ship, but efforts to use that containment method proved a failure.
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Photo by: Petty Officer 3rd Class Patrick Kelley / Caption by:

Top hat deck loading

On May 11, a containment chamber known as a "top hat" was loaded onto a ship's deck.

The unit was lowered onto the sea floor near the flow, and undersea robots positioned the cap over the flow. This effort failed too.

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Photo by: Petty Officer 3rd Class Patrick Kelley / Caption by:

Top hat lowered into Gulf

Remotely operated vehicles monitored and recorded the attempt to cover the well. The video display shows the "top hat" being lowered into the Gulf of Mexico on May 11.
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Photo by: Petty Officer 3rd Class Patrick Kelley / Caption by:

Aerial view of burning oil

In the meantime, other efforts to deal with the flow have been tried, such as burning oil off the water's surface.

Dark clouds of smoke fill the sky as oil burns during a controlled fire in the Gulf of Mexico.

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Photo by: Chief Petty Officer John Kepsimelis / Caption by:

Jeff Cantrell

Jeff Cantrell, vice president of Elastec/American Marine, relays information during a controlled burn.

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Photo by: Spc. 2nd Class Justin Stumberg / Caption by:

Drillship Discoverer Enterprise

In a process known as flaring, oil from the Deepwater Horizon wellhead was burned by the drillship Discoverer Enterprise on May 16.
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Photo by: Petty Officer 3rd Class Patrick Kelley / Caption by:

Oil booms deployed

Traditional booms have been used for at least two purposes during the crisis.

Here, Louisiana oil field diver Adam Shaw uses a hook to separate a more traditional oil boom that was to be used to trap oil for burning.

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Photo by: Spc. 1st Class (SW) Jeffery Tilghman / Caption by:

Boom protecting birds

Booms have also been put in place to try to protect sensitive areas such as Bretan Island, La., which is a nesting ground for endangered birds.

According to the government's official response site, more than 3 million feet of booms had been deployed in the Gulf as of Thursday.

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Photo by: Petty Officer 3rd Class Stephen Lehmann / Caption by:

Packing stockings with hair

Less-traditional booms have also been deployed.

Here, in Fort Myers, Fla., volunteers stuff hair into nylon stockings to make oil-soaking containment booms.

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Photo by: Vincent Koistinen / Caption by:

Nylons, tights, thigh-highs, knee-highs

The less-than-traditional booms use any kind of nylons--including tights, thigh highs, and knee highs--to hold hair, which is highly absorbent.
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Photo by: Matters of Trust / Caption by:

In Alabama too

Volunteers have filled booms in Alabama as well. These were filled at Felix's Fish Camp in Mobile in mid-May.
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Photo by: Matters of Trust / Caption by:

Levees on Elmer's Island

Last week, the Army National Guard was creating levees across beaches on Elmer's Island, just west of Grand Isle, La.

The levees are designed to help prevent oil from from reaching sensitive wetland habitats.

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Photo by: Petty Officer 3rd Class Patrick Kelley / Caption by:

Subsea dispersant injection system

Yet another way of trying to manage the flood of oil has been the use of chemical dispersants.

This image from BP shows how the chemical dispersant Corexit is being used to deal with the oil before it reaches the surface.

Hundreds of thousands of gallons of dispersant have been applied to the spill so far--an amount far greater than ever before used in U.S. waters.

Earlier this week the Environmental Protection Agency asked BP to curtail its use of Corexit over concerns about its effects on marine life. BP and the EPA have been arguing over the use of the dispersant. The agency is looking into whether there are less toxic alternatives available in large enough quantities.

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Photo by: Graphic provided by BP / Caption by:

Chemical bearing tanks

Preparing to spray the chemical dispersant Corexit from the air, U.S. Air Force Master Sgt. Brad Franken prepares a C-130 spray operating loadmaster from the 910th Airlift Wing at Youngstown-Warren Air Reserve Station in Ohio.

Members of the 910th Airlift Wing are in Mississippi to assist with the response to the Deepwater Horizon oil spill. The 910th AW specializes in aerial spray and is the Department of Defense's only large area fixed-wing aerial spray unit.
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Photo by: Tech. Sgt. Adrian Cadiz / Caption by:

Spraying dispersant

A U.S. Air Force chemical-dispersing C-130 aircraft drops Corexit into the Gulf of Mexico.
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Photo by: Tech. Sgt. Adrian Cadiz / Caption by:

NOAA probe

In yet another effort to help deal with the crisis, the National Ocean and Atmospheric Administration has been providing coordinated scientific weather and biological response services to federal, state, and local organizations.

Here, Nick Shay, professor of meteorology and physical oceanography at the University of Miami, and Bill Olney, a flight electronics technician, prepare to deploy an air-launched probe from a NOAA plane last week to study the Gulf of Mexico Loop Current and how best to prepare for the oil's movements.

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Photo by: NOAA / Caption by:

Bird cleanup

Some of the most tangible evidence of the oil spill's effect have been on the local wildlife population. Here, members of the Louisiana State Wildlife Response Team work to cleanse oil from a pelican.
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Photo by: U.S. Navy photo by Mass Communication Specialist 2nd Class Justin Stumberg / Caption by:

Tiger dam

On the beaches, containment efforts continue with gear including water-filled tiger dams such as this one being set up by National Guard members on the Gulf side of the Southwest Pass of the Mississippi Delta.
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Photo by: BP / Caption by:

Plastic bags and hazmat suits

Teams made up of representatives from the Coast Guard, the state of Louisiana, and workers contracted by BP are now faced with cleaning up oil that is washing up along scores of miles of the Louisiana coast and beyond.
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Photo by: BP / Caption by:

Shoveling oil-soaked sand

Cleanup of oil-contaminated sand, as here at Grand Isle, La., is often a very low-tech operation.
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Photo by: U.S. Coast Guard photo by Petty Officer 3rd Class Barry Bena / Caption by:

Shoreline cleanup and assessment

A member of a Shoreline Cleanup and Assessment Team walks along an oil-soaked beach in Port Fourchon, La. The big question for everyone: how long will this go on?
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Photo by: Petty Officer 3rd Class Patrick Kelley / Caption by:
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