One of the plans for the Forrestal was to make an artificial reef. Of course that too would have meant that asbestos, PCBs and any other nasties would have needed to be removed from it first.

It was also to be made a deep sea reef out of the reach of divers apparently because of design features that are carried on into modern US carriers.

In any case, due to the aformentioned way that the US guards its war tech, breaking the Forrestal up outside of the US would have been unthinkable, no matter what the cost.