Published: May 07, 2010 7:17 PM EDT

GULF OF MEXICO - Friday, May 7, 2010 marked day 18 of a Gulf of Mexico oil spill that began with an explosion and fire on April 20 on the drilling rig Deepwater Horizon, owned by Transocean Ltd. The blast killed 11 workers.

The rig was leased by BP PLC, which is now in charge of cleanup and containment. 

Oil has been pouring into the Gulf from a blown-out undersea well at about 210,000 gallons per day. The slick still threatens large sections of the U.S. coastline.

Diverting the flow of oil 

Underwater robots positioned a giant 100-ton concrete-and-steel box over a blown-out well at the bottom of the Gulf of Mexico on Friday as workers prepared to drop the device to the seafloor in a first-of-its-kind attempt to stop oil gushing into the sea.

A spokesman for oil giant BP LPC, which is in charge of the cleanup, said the box was suspended over the main leak just after noon EDT Friday and was being moved into position.

Several undersea cameras attached to the robots were making sure it was properly aligned before it plunged all the way to the bottom. The hope is that, perhaps as soon as Sunday, it will funnel up to 85 percent of the oil to a drilling ship.

When will the oil slick make landfall?

The quest to divert oil spewing from the ocean took on added urgency as it reached several barrier islands off the Louisiana coast, many of them fragile animal habitats.

Several birds were spotted diving into the oily, pinkish-brown water, and dead jellyfish washed up on the uninhabited islands. Residents of Louisiana, Mississippi, Alabama and Florida are anxiously waiting to learn when the huge oil slick might come ashore.

"Redneck Riviera" residents fear damage to the Gulf Coast shore

It's easy to see why generations of Southerners have flocked to the stretch of northern Gulf Coast affectionately called the "redneck Riviera" - and why they're worried about whether a massive oil spill is about to ruin their down-home playground.

For more than two weeks, millions of gallons of crude have been spewing from the ocean floor south of Louisiana. Matt Dagen, manager of a beach restaurant and entertainment complex, can't help but look at the emerald green waters and spotless Alabama beach and worry that a lifestyle, not just wildlife and dollars, is in peril.

Officials: Oil may pose health threat to humans

With the huge and unpredictable oil slick drifting in the Gulf of Mexico, state and federal authorities are preparing to deal with a variety of hazards to human health if and when the full brunt of the toxic mess washes ashore.

While waiting to see how bad things will get, public health agencies are monitoring air quality, drinking water supplies and seafood processing plants and advising people to take precautions. Little if any oil has reached land thus far, but shifts in wind speed and direction could propel the slick toward populated areas.

Authorities honed skill in last year's mock disaster exercise

Nearly eight years ago to the day, Coast Guard Vice Adm. Thad Allen was a commander, and played the leader's role in a mock oil disaster about 10 miles off the Louisiana Coast. Today, he's in charge of the government's real-life response to what was once the unthinkable and something earlier drills didn't anticipate - a deadly explosion on a British Petroleum rig and thousands of barrels of oil a day spewing from a deepwater well.

The 2002 exercise offered valuable insights, including how to set up command and response teams, and how to coordinate the response among private and public officials, Allen said. But he and others are haunted by things not learned, not anticipated and not followed from the earlier drill.