It's a commons problem.
This. If private groups were allowed to lease/purchase property rights to large geographic areas, they'd be able to set the rules for passage through the waters. International shipping lines, no problem. Fishing, no problem. Whaling, confiscation of ship & arrest of crew.
Of course, the greenpeace folks are probably too far along the path to militant communism to believe in ownership of anything, so they'd not actually be able to take a useful course of action.
Yeah, this sounds great. Japan and China could buy the whole ocean outside of our territorial limits and restrict our free trade with the entire rest of the world.
Ships would have to zig-zag all over the map to go through what was previously a straight line, like not touching the red squares on a checkerboard.
Theoretically, you could buy a circle of plots and the owner of the donut-hole would have no access to their waters.
Shipping would have increased tariffs like toll booths on the open seas, if the owners wanted, and you can bet they'd enforce it. Some could pass, others could not, depending on their international trade agreements.
They're called "International Waters" for a reason.
And, who exactly would they buy the rights from? Nobody owns them, so, start wars to claim the seas, and the winner gets to sell their conquests to the highest bidder?
I'm sure the US Navy would approve. We haven't had a good war at sea in 60 years.