The major problem with oceanic pollution is that standards vary between countries and policing is haphazard to non existant. The EU has comprehensive controls in place and presumably any EU registered ship could be audited to those standards. However upwards of 40% of freight shipping is under flags of convenience where the regulatory regime is "relaxed" Many offshore rigs separate their waste streams and have a zero discharge policy(all waste is transferred to shore for legitimate disposal), others such as greenpeace have been observed throwing gash over the side. Until there is full international cooperation, detailed legislation and comprehensive auditing, the oceans will continue to be filled with garbage.