Since rivers run into the ocean, most forms of fresh water pollution eventually affect the ocean as well.
Types of freshwater pollution involve urban run off, agricultural run off, and industrial pollution. Thermal pollution is release of heated water into rivers that may kill fish by thermal shock.
Untreated municipal sewage can be released into rivers or the ocean, as can industrial waste.
Oil spills from broken pipelines affect fresh water aquifers. Oil spills from tankers (Exxon Valdez, e.g.) or underwater drilling (Deepwater Horizon) affect salt water. Fishing debris is an ocean issue. Plastics and other non-degradable garbage in the ocean can collect in huge vortices such as the `great eastern garbage patch` an area of the ocean twice the size of Texas filled with waste.