Various embodiments of an underwater power generation apparatus are provided. In one embodiment, an underwater power generation apparatus is provided, comprising: a conduit having a bore defined by an interior surface of the conduit, the bore comprising a void extending about a length of the conduit; an exterior cylinder, the conduit oriented within the exterior cylinder, and the conduit rotatable relative to the exterior cylinder; at least three bearings oriented between the conduit and the exterior cylinder; at least one blade having a first blade direction, the at least one blade having a first blade direction oriented on the interior surface of the conduit at a first end of the conduit; and at least one blade having a second blade direction, the at least one blade having a second blade direction oriented on the interior surface of the conduit at a second end of the conduit.