To determine what percentage of the Earth's surface is covered in water, we can look at the options provided:
1. 45 percent
2. 63 percent
3. 70 percent
4. 82 percent
By analyzing the Earth's surface and the percentage of it that is covered by oceans, seas, rivers, and other bodies of water, we find that the correct percentage is 70 percent.
Therefore, the answer is 70 percent.
