The U.S. Coast Guard on Monday began unloading more than 40,000 pounds of cocaine seized from three ships off the Central American coast, including one bust called the largest in U.S. maritime history.

The Coast Guard boarded a 330-foot ship heading north off the Pacific coast of Panama last month and discovered about 38,000 pounds of cocaine in two shipping containers, officials said.

The bust was the largest single sea-based seizure of cocaine by a U.S. agency, Coast Guard Petty Officer Brian Leshak said.

In another bust off Panama's coast last month, a Coast Guard cutter chased down a cigarette-style speedboat carrying about 2,000 pounds of cocaine, officials said.

The Coast Guard in February intercepted an Ecuadorian-flagged fishing vessel allegedly loading cocaine into speedboats off Mexico's coast.

The fishing vessel's crew set fire to their ship to destroy the evidence and tried to flee in the speedboats, but were caught, according to the Coast Guard. About 900 pounds of cocaine were seized.

The Coast Guard detained a total of 32 crew members in the three busts.

The cocaine, with an estimated street value of $500 million, will be turned over the U.S. Drug Enforcement Administration, which will take the drugs to Miami to be destroyed, Leshak said.