ON THE GULF OF MEXICO - A growing collection of crippled equipment littered the ocean floor Sunday near a ruptured oil well gushing crude into the Gulf of Mexico, the remnants of a massive rig that exploded weeks ago and the failed efforts since to cap the leak.
On the surface, nearly a mile up, a fleet of ships maneuvered to deploy the latest stopgap plans hatched by BP engineers desperate to keep the Deepwater Horizon disaster from becoming the nation's worst spill. An estimated 3.5 million gallons has risen from the depths since the April 20 explosion that killed 11, a pace that would surpass the total spilled in the Exxon Valdez disaster by Father's Day.
A day after icelike crystals clogged a four-story box that workers had lowered atop the main leak, crews using remote-controlled submarines hauled the specially built structure more than a quarter-mile away and prepared other long-shot methods of stopping the flow.
Chief operating officer Doug Suttles said BP was thinking about putting a smaller containment dome over the massive leak, believing that it would be less vulnerable. The smaller dome could be ready to deploy Tuesday or Wednesday.
"We're going to pursue the first option that's available to us and we think it'll be the top hat," Suttles said.
The company was also now debating whether it should cut the riser pipe undersea and use larger piping to bring the gushing oil to a drill ship on the surface. The third option would use a tube to shoot ground-up materials into the well's blowout preventer, a process that could take two to three weeks.
As BP weighed its options on the mainland, waves of dark brown and black sludge crashed into a boat in the area above the leak. The fumes there were so intense that a crewmember of the support ship Joe Griffin and an AP photographer on board had to wear respirators while on deck.
A white cattle egret landed on the ship, brownish-colored stains of oil on its face and along its chest, wings and tail.
Meanwhile, thick blobs of tar had washed up on Alabama's white sand beaches, yet another sign the spill was spreading.
It had taken about two weeks to build the box and three days to cart the containment box 50 miles out and slowly lower it to the well a mile below the surface, but the frozen depths were just too much.
Company and Coast Guard officials had cautioned that icelike hydrates, a slushy mixture of gas and water, would be one of the biggest challenges to the containment box plan. The crystals clogged the opening in the top of the peaked box, Suttles said, like sand in a funnel, only upside-down.
"We never believed the hydrates could actually plug up a 12-inch opening and they did, which means they're forming very rapidly and in large quantities," Suttles said.
The containment box plan, never before tried at such depths, had been designed to siphon up to 85 percent of the leaking oil.
The original blowout was triggered by a bubble of methane gas that escaped from the well and shot up the drill column, expanding quickly as it burst through several seals and barriers before exploding, according to interviews with rig workers conducted during BP PLC's internal investigation. Deep sea oil drillers often encounter pockets of methane crystals as they dig into the earth.
As the bubble rose, it intensified and grew, breaking through various safety barriers, said Robert Bea, a University of California Berkley engineering professor and oil pipeline expert who detailed the interviews exclusively to an AP reporter.
Associated Press writers Ray Henry and John Curran in Louisiana, Jay Reeves and Brent Kallestad in Florida and Sarah Larimer and video journalist Rich Matthews in Alabama contributed to this report.