Which location contains Earth's saltwater?

• A. Oceans
• B. Lakes
• C. Rivers
• D. Groundwater

Answer: (A)

Earth's saltwater is found mainly in the oceans. Oceans cover most of the planet's surface and hold the vast majority of the dissolved salts that make seawater salty, with a typical salinity around 3.5% (about 35 grams per liter). Lakes and rivers are part of the freshwater portion of the water cycle; they have low salinity because rain and runoff bring in fresh water and salts are not accumulating there in the same way. Groundwater is also generally fresh, stored underground, though saltwater can intrude into coastal aquifers in some places. While some inland lakes are salty, they don't contain the bulk of Earth's saltwater—the oceans do.