Tides

This picture shows the ocean in Puerto Rico at low tide, at high tide the water about reaches the hotels. Tides are caused by the differences between the gravitational force between the Moon and the Earth. High tides are the result of the moon pulling the earth. The Earth's side closest to the moon has a greater gravitational pull acting upon it. When the moon pulls the Earth, it creates these tidal buldges that create high and low tides. High tides would be the side closest to the moon and its opposite side. Tides happen twice a day every six hours.