The Mexican Navy says X-ray machines helped uncover the haul
The Mexican Navy says it has seized more than a tonne of cocaine hidden inside the carcasses of frozen sharks.
Armed officers found slabs of cocaine inside more than 20 sharks aboard a freight ship in the Gulf coast port of Progreso in Yucatan state.
Correspondents say cartels are coming up with increasingly creative ways of smuggling drugs into the US.
Shipments of cocaine have also been discovered hidden inside sealed beer cans, religious statues and furniture.
"We are talking about more than a tonne of cocaine that was inside the ship," said Mexican Navy Commander Eduardo Villa.
He said X-ray machines and sniffer dogs had helped to uncover the haul.
"Those in charge of the shipment said it was a conserving agent but after checks we confirmed it was cocaine," he said.
In another development on Tuesday, the Mexican Navy unveiled what it described as one of the largest methamphetamine labs ever found in the country.
When officers stumbled across the enormous holding tank in a remote part of the northern state of Sinaloa last week they thought it might be used to water a marijuana plantation.
Instead, the tank fed water into two enormous sheds where investigators found 12,905 gallons (49,640 litres) of ephedrine, a chemical used to make methamphetamine.
Officials said it was enough to produce 40.2 tonnes of the drug, or about 309 million individual doses.
So far this year more than 2,700 people have died in drug-related violence in Mexico. Last year about 6,300 were killed.
Mexican President Felipe Calderon has committed some 45,000 troops and federal police to try to crush the country's powerful cartels.