* Largest bodies of salt water on Earth
* Cover about 71% of the Earth's surface
* Five oceans: Pacific, Atlantic, Indian, Arctic, and Southern (Antarctic)
* Average depth: 3,700 meters (12,100 feet)
* Deepest point: Challenger Deep in the Mariana Trench (10,911 meters or 35,797 feet)
Seas
* Smaller than oceans but still large bodies of salt water
* Usually partially enclosed by land
* Some seas are connected to oceans, while others are landlocked
* Examples of seas: Mediterranean Sea, Caribbean Sea, North Sea, Baltic Sea
* Average depth: 1,000 meters (3,280 feet)
Rivers
* Natural channels of water that flow from high elevations to lower elevations
* Eventually empty into oceans, seas, or lakes
* Can be perennial (flow year-round) or intermittent (flow only during certain times of the year)
* Examples of rivers: Nile River, Amazon River, Mississippi River, Yangtze River
* Average depth: 1 meter (3 feet)
Lakes
* Bodies of fresh or salt water surrounded by land
* Can be natural or man-made
* Natural lakes are formed by glaciers, volcanoes, earthquakes, or other geological processes
* Man-made lakes are created by dams or other structures
* Examples of lakes: Lake Superior, Lake Baikal, Lake Tanganyika, Lake Titicaca
* Average depth: 50 meters (164 feet)
