Ocean dumping involves disposing of various materials directly into ocean waters, including garbage, construction debris, sewage sludge, dredged materials, chemicals, and nuclear waste. Some hazardous and nuclear wastes are also disposed of illegally but pose serious dangers to aquatic and human life. The document discusses incidents where nuclear and toxic waste dumping in Somalia in the 1990s and off the coast of Japan in 2011 contaminated the marine environment and local populations with radiation and other pollutants. International laws now largely ban ocean dumping due to its harmful environmental and health impacts.