1. Definition and characteristics of the ocean:

The ocean refers to the waters with salt water environment on the earth. Its characteristics include a wide range, different depths of seabed topography, salt water and contact with land. The interior of the ocean is divided into different regions, including shallow sea, continental shelf, basin and trench.

2. Geographical distribution of oceans:

The oceans are distributed around the continents on the earth's surface and are surrounded by land. There are five oceans in the world, namely Pacific Ocean, Atlantic Ocean, Indian Ocean, Antarctic Ocean and Arctic Ocean. In addition, there are some smaller oceans and bays, such as the Mediterranean Sea, the Red Sea and the Persian Gulf.

3. The role and significance of the ocean:

The ocean plays an important role in the natural system of the earth. First of all, the ocean has a significant impact on climate and weather, and maintains the temperature balance of the earth by storing heat and adjusting the climate. Secondly, the ocean is an important habitat of the earth's biodiversity, which is pregnant with rich marine biological resources. In addition, the ocean also provides important transportation channels and opportunities for resource development.

4. Marine biodiversity:

The ocean is one of the most biodiversity-rich ecosystems on earth. It contains all kinds of creatures, from tiny plankton to huge whales, coral reefs and seaweed beds. Protecting marine biodiversity is of great significance for maintaining the stability and sustainable utilization of marine ecosystems.

5. Development and utilization of marine resources:

There are abundant marine resources, such as fishery resources, mineral resources and energy resources. Marine fishery is one of the important sources for human beings to acquire protein. In addition, the ocean is rich in energy and mineral resources, such as oil, natural gas and minerals.

6. Protection and sustainable utilization of marine environment:

With the increase of human activities, the ocean is facing many environmental problems, such as pollution, overfishing and ecological destruction. In order to protect the marine environment and make sustainable use of marine resources, the international community has taken a series of measures, including establishing marine protected areas, strengthening monitoring and management, promoting scientific research and promoting international cooperation.