Most of the world s polar bear population lives in Canada. Scientists define oceans as the whole bodies of water that cover nearly three-quarters of the planet s surface. All the world s oceans are actually one vast marine ecosystem, connected by great currents flowing from hemisphere to hemisphere. Also included are seas, such as the Beaufort and Mediterranean. Oceans and seas can reach depths of 10 kilometres.
Oceans are saltiest where they are very hot, such as the Red Sea, or very cold, such as the Arctic.
Unlike countries, oceans have no boundaries. No one knows exactly where one ocean becomes another. Sooner or later, all water drains into the ocean. Learn all you can about oceans and the problems they face. Discover all the ways in which you and your community are connected with the ocean how you need it to survive and how your actions help or harm marine ecosystems no matter where you live.