The news was not announced over the weekend so as not to endanger ongoing investigations, a navy spokeswoman told ANP.
The 80 bales of cocaine were found in a special secret compartment on board the ship D'Mary sailing under the flag of the African island state of Sao Tome and Principe.
The seizure was done together with the American authorities. The drugs and eight crew members of the boat have been turned over to the US authorities, ANP said.