What causes tides?
Google.
They are caused by the moon. You can read more about it here.
http://home.hiwaay.net/~krcool/Astro/moon/moontides/
The gravitational pull of the Moon and the Sun primarily causes tides on Earth. To understand why, let's break it down.
The Moon's gravitational force exerts a pull on Earth. However, the force is stronger on the side of Earth closest to the Moon and weaker on the opposite side. This difference in gravitational pull leads to a tidal bulge, where the water is pulled towards the Moon, causing a high tide.
On the other side of Earth, there is another tidal bulge, referred to as the "opposite" or "distant" high tide. This bulge is formed because the Moon's gravitational pull is weaker here compared to the center of the Earth.
Similarly, the Sun's gravity also affects the tides, although its impact is approximately half of the Moon's due to its distance. When the Sun, Moon, and Earth are aligned during a full moon or new moon, their gravitational forces combine, resulting in particularly high tides called spring tides. On the other hand, when the Sun and Moon are at a right angle to each other during the first and last quarter moon, their gravitational forces partially cancel each other out, leading to lower tides called neap tides.
It's important to note that other factors, such as the topography of the coastline, the shape of ocean basins, and the Coriolis effect, can also influence tidal patterns locally. However, the primary cause of tides is the gravitational interaction between the Moon, Sun, and Earth.