A mystery armed unmanned sea drone washed ashore on a Greek island, with authorities investigating. Footage shows fishermen towing the vessel, that was discovered inside a coastal cave on the holiday hotspot island of Lefkada, to a nearby harbour on Thursday (7 May). It was moved on Friday to a naval base on the mainland for inspection, according to Greece’s public broadcaster ERT. Ukraine has used drone boats in the Black Sea to fight Russian naval vessels, with Moscow having also developed