Transport Malta has laid 38 buoys around the coast of the Maltese Island to mark the distance of 200 metres or 300 metres from the coast where speed limits have to be observed.
A number of the buoys mark a speed limit of 10 knots while others signal the 5 knot limit.
More details on the speed limits at http://www.transport.gov.mt/admin/uploads/media-library/files/Not%2025%20of%202015.pdf