BP said the 4-inch tube is working, siphoning 84,000 gallons a day to a ship, oil that otherwise would have poured into Gulf waters. But oil continues to bleed into new areas, and experts fear it could wind its way up the East Coast.
Some experts agree with BP that the insertion tube has made significant headway in controlling the spill.
"The riser insertion tube can only siphon off a certain amount of the oil, which is probably about 30 to 40 percent of the oil that's coming out of the tube," said Satish Nagarajaiah, a professor of civil and mechanical engineering at Rice University. "I think it's good progress."
But others, including residents who depend on the ocean for their livelihoods, say it's not good enough. Some who rely on Florida's $60 billion a year tourism industry say the damage already may be done.
"We know of people who're saying they're not coming in June because of the oil," said Spencer Slate, who owns a dive center in Key Largo. "Nothing functions down here without tourism."
ABC's Jake Tapper, Ayana Harry, Azfar Deen and The Associated Press contributed to this report.