However in the coastal regions the actual levels of the tides depend on other factors like the winds, the depth of the waters, and the shape of the coast line. Although it does not seem to be much, the effect is especially noticeable during Spring tides and Neap tides. Spring tides are caused when the Moon and the Sun and the Earth are all in the same line, and the gravitational force of the Sun and the Moon both are acting in the same direction. This causes very high levels at High Tides and very low levels at Low tides. These are known as Spring tides, and could be caused even if the Moon and Sun are at opposite ends of the Earth.
Spring tides occur approximately twice a month during the time of the Full Moon and the New Moon.
Approximately every 18 months during the Spring tide the Moon is at its closest distance to the Earth called its perigee. This gives rise to gravitational forces that are so strong, that they cause extremely high levels of tides. This is known as the Proxigean Spring Tide. When the gravitational forces of the Sun and the Moon are perpendicular to each other, Neap tides occur. Since the gravitational force of the Sun is pulling in a direction opposite to that of the Moon, a part of the effect of the Moon s gravitational force is cancelled out.