As a marine scientist with a focus on physical oceanography, I can explain the phenomenon of ocean tides. The main cause of ocean tides is the gravitational attraction of the moon and, to a lesser extent, the sun. The moon's gravity causes the oceans to bulge out towards it, creating a tide. This bulging effect is due to the moon's gravitational pull being stronger on the side of the Earth facing the moon, which stretches the water outwards. Additionally, there's another bulge on the opposite side of the Earth, which is a result of the Earth's own gravitational pull being slightly weaker there, causing the water to bulge away from the moon. The Earth's rotation then brings different parts of the ocean into alignment with these bulges, leading to the two high tides and two low tides we experience each day. read more >>

The gravitational attraction of the moon causes the oceans to bulge out in the direction of the moon. Another bulge occurs on the opposite side, since the Earth is also being pulled toward the moon (and away from the water on the far side). Since the earth is rotating while this is happening, two tides occur each day.read more >>