Even the great whales are victims - several have been found dead with plastic bags and sheeting in their stomachs. Sometimes an animal accidentally swims into a piece of plastic and becomes ensnared, unable to escape. Curious seal pups are often attracted to floating debris and become entangled. Birds not only become entangled in plastic connector rings and fishing line, but also use plastic as nesting materials, which can create death traps for their young. Plastic debris is not just a problem for wildlife.
Plastics also can be a floating menace to navigation.
Boaters report that plastic rope and line fouls propellers and that plastic bags and sheeting clog seawater intakes and evaporators, causing engine failure, costly repairs, and annoying delays. This type of vessel disablement can be life threatening. Styrofoam is permanent garbage. It can't ever become part of the Earth again. Styrofoam is a danger to sea animals.