The extent of the problem of pollution from vessels has been reviewed and evaluated, and recommendations for corrective and preventive action have been developed. All navigable waters of the United States have been considered in the study -- coastal waters with their bays, sounds, and inlets and the myriad of rivers, lakes and canals comprising the Nation's major inland water resources. This report represents an initial assessment of the degree and magnitude of the problem which may be further refined by future studies. The great diversity in vessel size, type, usage and operating conditions is recognized.