Assembly of turret and disconnectable buoy, in which the turret at its lower end and the buoy at its upper end are provided with mating coupling provisions. The coupling provisions comprise an annular projection protruding from one of the turret and buoy towards the other of the turret and buoy and a correspondingly shaped annular recess on the other of the turret and buoy for receiving the annular projection. The annular projection has a base which is wider than a top thereof, whereas the annular recess has a top which is wider than a base thereof.