Tides are caused by the gravitational force exerted by the Moon on our planet. This force causes the ocean to bulge out in the direction of the Moon, making the tide rise. As the Earth is also pulled towards the Moon, the ocean on the side facing away from the Moon also bulges out. So it is high tide there as well. In the region between the two bulges (high tides) the water level decreases, causing low tides. Tides are higher in the tropics due to the bulge of the equator. Many forms of life on the coast are tailored to the cycle of tides.