Around 3.5 tonnes of hashish, two cars, a speedboat and 1,500 litres of fuel were seized by Aljezur GNR police at Vale Figueiras beach on May 24.
A police spokesman told Lusa news agency: “We detected, through night surveillance cameras, suspicious movements in the sea and on the beach, which led us to consider a possible landing of drugs.
“There were at least six people, including the crew of the boat and the drivers of the vehicles, waiting on the beach,” he added.
One of the suspects was arrested and will be presented in court.
GNR police are conducting investigations to find the other suspects, who fled the scene.