The Moon influences diverse phenomena of the terrestrial surface, one of them is the formation of tides, that consist of that every 12 hours with 25 minutes, approximately, the oceanic waters rise of level.
The tides are produced by the gravitational attraction of the Moon and to a lesser extent by the attraction of the Sun. As you will remember, the force of gravity besides depending on the mass of the objects that are attracted, also depends on the distance that separates them; that is, the closer they are, the greater the force of attraction that exists between them.
So the smaller the distance between the Earth and the Moon, due to the elliptical orbit of the latter, the gravitational attraction between them will be greater. This causes the waters of the oceans that are in front of the Moon to rise, while the waters on the opposite side remain at their normal level.
Water rises a few centimeters in closed seas, like the Mediterranean; and in some areas such as the Bay of Fundy, in Nova Scotia, Canada, the highest tide reaches 15 meters in height.
If the only star in the sky were the Moon, we would notice a periodic rising of the water as the Moon moves on the horizon. However, the Sun is another star that exerts gravitational attraction on the Earth, therefore it also produces tides, although less intense than those of the Moon.
In Mexico, in the state of Campeche, fishermen use the tides to catch the shrimp, because when the tide rises it enters the estuaries loaded with shrimp, and when it goes down, it returns to the sea. So when the tide comes down, the fishermen place their nets to catch them.