Question

what happen when we put wire of current in ocean

Answer 1

ocean water is quite conductive so the current will be immediately grounded  and the generator will be short circuited (ruined or automatically shut down) you might stun a few nearby fish however.

Answer 2

What will happen if electric current is passed to an ocean?

Suppose you put a live wire into the Indian ocean or cables underneath the ocean get short-circuited - what will happen? Will a... More


Tom Quetchenbach, works at Humboldt State University

This is actually done routinely as part of some high-voltage DC transmission lines. For example, the Pacific DC Intertie is a 3100 MW DC transmission line running from Oregon to Southern California. The line can operate in monopolar mode, in which the current is transmitted over the wires in one direction and the return path is through the ground. From the Pacific DC Intertie Wikipedia page, "the Sylmar grounding system [in Southern California] is a line of 24 silicon-iron alloy electrodes submerged in the Pacific Ocean at Will Rogers State Beach suspended in concrete enclosures about one meter above the ocean floor."

The important thing is that even though the current is quite high (over 3,000 amps), the current density is low, because the electrode is large. Even though you won't get shocked from swimming in the ocean in Southern California, there are some environmental impacts from such a system; for example, the electrodes may produce chlorine from the salt in seawater, and the current can cause electrochemical corrosion in buried or submerged metal objects.