These are groups approaching the issue of marine debris from a number of different angles.
The National Oceanic and Atmospheric Administration (NOAA) works to educate the public and support projects that help communities reduce marine debris.
One Less Straw seeks to inform people about the number of plastic straws being used daily and the impact they have on the environment.
The Ocean Conservancy is fighting for Trash Free Seas.
A National Geographic Society encyclopedia entry on marine debris.
Marine Debris Info, a clearinghouse for sharing knowledge on marine litter.
The United Nations Environmental Program page on marine litter.