To answer the OP and to prevent confusion about grounding, the ocean is not an acceptable grounding point as far as the NEC is concern. On float houses, houses on piles, boat houses, any structure which are "permanently" attached to the shore falls under the local electrical code.
In regards to the OP and clarify some of the following posts, the grounding electrode system (i.e. Rods, pipes, plates, rings, etc.) have nothing to a structure's internal wiring or our trade calls, equipment grounding conductors. They both do totally separate things. The simplest way of putting it is the grounding electrode system protects a structure from external sources like near by lightening strikes and faults in the distribution system like a faulty transformer or downed primary on a secondary line. The equipment grounding protects the same structure from internal faults like ground faults. With that said, let the public lashing commence but in a new post
