The authorities in Colombia have revised the total of drugs seized in a haul on Monday from around 25 tonnes of cocaine to just over 13 tonnes.
Colombia is the source of most of the world's cocaine
It was found in 1,000 separate packages near the town of Pizarro, west of the capital, Bogota, buried in an estuary accessible only by sea.
Defence Minister Juan Manuel Santos had said on Monday the haul was the "biggest in the history of Colombia".
The confusion was blamed on errors made in the initial sight count of the drug.
The drugs were discovered when the Colombian navy intercepted several speedboats off the Pacific coast near the border with Panama.
A navy statement said that traffickers usually carry the drugs in packages weighing 20kg-25kg. However, when weighed, the packages in Monday's haul were found to be considerably lighter. The final total was 13.2 tonnes.
The haul remains the largest drugs seizure in Colombia so far this year. But in May 2005, 15 tonnes of cocaine was found in jungle near the Pacific coast.
Although no-one was arrested after the seizure, the drugs are believed to belong to one of the country's largest drugs cartels, the Norte del Valle group.
Colombia is the world's largest producer of cocaine, supplying 90% of the drug consumed in the US alone.
President Alvaro Uribe is in Washington for talks on the US-backed Plan Colombia, which provides American money for anti-narcotics and counter-insurgency operations in Colombia.