The tides are caused by the gravitational pull of the Moon on Earth’s oceans. In fact, the Moon’s gravitational pull attracts everything, even the land and mountains, though being rigid and fixed they do not move. But not so with the oceans. Being an unbroken stretch of water, spread over almost 70% of the Earth’s surface, the Moon’s pull can easily draw water away from one part and pile it up at another which show up as tides. However, this is not possible in a small body of water such as a lake. Here the total surface area and volume of water is too small to produce any perceptible change in the level as happens in tides.