What Causes Tides - Why do Tides Occur
High Tide Times

Here is a simple explanation for What Causes Tides, along with High Tide Times and helpful information about local Martha's Vineyard tides and tide charts.

Why do Tides Occur?

Gravitational attraction between the Earth, the moon and the sun causes the ocean tides.

The mass of the moon and sun exert a pulling force on earth. The result is that the waters of the ocean are deeper on the sides of the earth closest to and farthest away from these pulling forces.

Rather than being distributed in an equally thick layer on all sides of the earth, the water becomes "thin" on two sides of the earth because it has been pulled to the side closest to these forces. The water on the side of the earth that is furthest from the pulling forces also becomes deep because the earth itself has been pulled towards the pulling forces.

This is best illustrated with the following diagram from the National Oceanic and Atmospheric Administration website...