That the rise and fall of the tide is driven primarily by the gravitational pull of the Moon and the Sun is common knowledge, but not all tides are controlled by such a standard mechanism. Researchers working on Loch Ness in Scotland found that rather than the loch's tide being driven directly by this so-called astronomical tide, it is also controlled by a process known as ocean tidal loading. Loch Ness lies just 13 kilometers inshore from the North Sea. The astronomical tide redistributes the ocean to such an extent that the changing mass of water along the coast deforms the seafloor. As the ocean tide ebbs and flows, the surface of the Earth rises and falls.