There is nothing above the sovereign nations and they are only bound by their treaties, bilateral and multilateral - despite having a name like "United Nations Convention on the Law of the Sea", this is not some law which UN could pass or modify, it's a treaty which is binding only on those who sign it, and any modifications to add extra restrictions it will be binding only to those ships whose countries agree to these restrictions. UN (and any other international organization) is subservient to the sovereign countries or a place of discussion, not some "world government" above them.
There is nothing above the sovereign nations and they are only bound by their treaties, bilateral and multilateral - despite having a name like "United Nations Convention on the Law of the Sea", this is not some law which UN could pass or modify, it's a treaty which is binding only on those who sign it, and any modifications to add extra restrictions it will be binding only to those ships whose countries agree to these restrictions. UN (and any other international organization) is subservient to the sovereign countries or a place of discussion, not some "world government" above them.