The relevant point is not how large the body of water is, but how close a person is to the toaster. The body of water is only relevant in so far as there’s a limit to how far away you can get in a bathtub. But someone that close in a lake or ocean would be just as bad off.
Size of body of water does not matter. People get injured or die from swimming near boats with shore-power faults in lakes, rivers, ocean harbors, etc.