NOVELTY - The power generating apparatus (4) has a generator (8) that includes a stator which defines an axis of the generator and a rotor (12) that is arranged for rotation about the stator. A turbine (14) is provided with a casing (16) and a blade (18) that is supported on the casing. The casing of the turbine is enabled to provide the rotor of the generator, by mounting rotor for rotation about the stator of the generator. The axis of the generator is vertical and the turbine is maintained on stator housing by the action of gravity.    USE - Underwater power generating apparatus e.g. vertical axis power generating apparatus for generating electricity from tidal currents, used in deep sea environment.    ADVANTAGE - The power generating apparatus provides a very simple and robust installation, so that the cost of energy generation can be reduced. Due to the simplicity of the structure of power generating apparatus, the resources can be directed into making the few components as reliable and efficient as possible, thus ensuring that intervention during the operating life of the installation is not required. Significant capital cost reductions, maintenance requirements, and improvement in reliability can be achieved due to the removal of so many systems that are necessary in horizontal axis apparatus. The power generating apparatus does not require split rings or sub-sea connection using wet-mate connections, and does not require any dry space or seals, so that the power generating apparatus is highly suitable for deep water sites. The power generating apparatus can be designed to support turbines of varying sizes to suit different sites, using a common generator and foundation structure. The versatility of the power generating apparatus ensures that to be equally suited to shallow sites as to deep water, or to any other conditions specific to particular geographical areas.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a power generating installation.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the underwater power generation installation.    Power generating apparatus (4)    Generator (8)    Rotor (12)    Turbine (14)    Casing (16)    Blade (18)