Offloading hydrocarbons from subsea fields

A subsea hydrocarbon export system 10 having a riser tower 20 with a riser column 22 extending from a seabed location 14 to a sub-surface buoy 24 that supports the riser column in an upright orientation. A subsea connector 28 is operable underwater to couple the riser column temporarily to a hose 26 suspended from a surface shuttle tanker vessel 16 for an export operation and to release the hose after the export operation. In an alternative embodiment there is provided a method of installing a subsea hydrocarbon export system by lowering a major lower section 22L of a column into water beneath an installation vessel and suspending the lower section from the installation vessel. Then a buoy 24 and a minor upper section 22U of the column are positioned over the suspended lower section and the upper section is joined to the lower section to complete the column. Finally the buoy and the completed column are lowered into the water beneath the installation vessel and where a lower end of the column is anchored at a seabed location, the buoy then being at a sub-surface location.