(CNN) -- More than 500 kilos of cocaine have been found hidden near the engine room of an oil tanker in the Spanish port of Tarragona, Spain's Guardia Civil said in a statement Saturday.
The boat left Maracaibo in Venezuela for Egypt in mid-September. It was in the port of Tarragona when Spanish police -- as part of routine checks of any boat coming from "hot routes" -- checked the boat, the statement said.
Agents entered the boat and spotted several bags in a small boat room that is normally empty.
The room is difficult to access from the inside of the vessel, so police entered the tight space from the water and found 510 kilos of cocaine in 14 packages strapped together.
Authorities believe drug smugglers using boats to transport their products will place stashes in small rooms that are difficult to access from inside the vessels. They will get scuba drivers to access the rooms and retrieve the drugs when the boat is anchored.
There was no word on any arrests.