Ans. Tides occur in the ocean due to the gravitational pull of the moon and the sun. When the gravitational force of the moon is stronger on one side of the Earth, it creates a high tide. On the opposite side, there is also a high tide due to the centrifugal force caused by the Earth's rotation. The areas between these high tides experience low tides. The sun also contributes to tides, but its effect is about half as strong as that of the moon.