What percentage of Earth's water is seawater?

• A. About 97.5 percent
• B. About 2.5 percent
• C. About 35 percent
• D. About 68 percent

Answer: (A)

Seawater is the largest reservoir of Earth's water because oceans cover most of the planet and contain about 97.5% of all Earth's water. The remaining water is freshwater, roughly 2.5%, with most of that trapped in glaciers and groundwater rather than in readily accessible rivers and lakes. So, the correct answer is about 97.5%. The other numbers refer to freshwater shares or how that freshwater is distributed, not seawater.