The sea doesn't actually go anywhere when the tide goes out. The water is being pulled away from the coastline by the gravitational forces of the Moon and the Sun.
As the Earth rotates, different parts of the coastline move through areas of higher and lower sea level. When your local area moves away from the tidal bulge, the sea level falls and the tide goes out.
The water that leaves your beach or harbour flows out into the surrounding sea. At the same time, another area of the coastline is experiencing a rising tide as water moves towards it.
So, when you see the tide going out, the water hasn't disappeared — it has simply moved elsewhere as part of the continuous tidal cycle.
Read more about this over on our recent blog post.
