I have snorkeled all along the Atlantic coast from Wrightsville Beach to Key West, the Gulf from the Florida Panhandle to Louisiana and parts of Texas, several of the islands of the Bahamas, Jamaica, Puerto Rico, and the Yucatan Peninsula of Mexico. The vast majority of the trash I have found is plastic. Although some small amount may come from careless beach-goers or local landfills, it appears that much of it comes from cruise ships. I am not aware of any authority able to fine a cruise ship in international waters for littering, and it is nearly impossible to prove the point of origin for anything that washes up on a beach. Short of deploying fleets of skimmer ships to collect the plastic or completely banning plastic on cruise ships, it seems the best option would be to develop biodegradable plastics.
It is pretty hard to ask a government to put a stop to what the government itself has done. After WW II, our government (and others, I'll wager) dumped al kinds of war machines and weapons into the Gulf - and who know where else. When protests rose, the alibi was that these machines make good hiding places for creatures who live in the ocean.
Same with rivers and lakes. I am sure most of you have seen the suggestion that discarded Christmas trees be tossed into rivers to serve as nesting places.
Two sides to every story. Yes, something needs to be done but the ones doing it only say "let George do it". Can we win?