Method of supplying oil from a first floating structure to an offloading structure, includes providing a flexible duct extending between the two structures at a water depth of between 50 m and 500 m, the duct including a flexible elastomeric material and having an internal diameter of at least 600 mm and a length of between 1500 and 3000 m, providing at least one pump at the first structure and pumping the oil through the duct at a pressure between 5 bar and at a flow rate between 1000 and 50,000 m3/hr, providing a single flexible duct, and providing a wall thickness of the duct such that at water temperatures between 2° C. and 20° C., the oil has at the first structure an inlet temperature Tin and at the second structure an outlet temperature T0 that Tin-T0 is smaller that or equal to 15° C., preferably smaller than 5° C.