Tides
The moon's gravity pulls water that is in oceans, lakes, ponds, stream, and rivers that make big bumps on both sides of the planet in the ocean. The bump closer to the moon is caused by the moon pulling water toward itself. The one opposite of the moon is caused by the moon pulling away from the water on that side. If you are on a shore and the moon is directly over your head you should see high tides. Even if its directly overhead on the opposite side of the world you will see a high tide. A coastal city sees a high tide every 12 hours and 25 minutes or so.