You&#x27;re right for borders between existing nations, however, the expected result of a large sea level rise will include a number of current countries being eliminated.<p>I wouldn&#x27;t expect a non-existent nation to keep it&#x27;s territorial waters, instead it will be re-distributed among its neighbours (possibly depending on some deal with relocation of their current inhabitants), but no matter how you do that, there is a lot of potential for disputes.