That totally inauspicious-looking building at the end of the pier is the Newlyn Tidal Observatory. And it’s here—right here in Newlyn—where the mean sea level for all of the Uk is identified. This measurement forms the starting point for leveling the whole of the UK. And not just sea levels: how we calculate height above sea level has a direct impact on how high we measure mountains and how deep we measure valleys. You can read all about it here but the short answer is: six years.