Tide clock

This tide clock is in Maryport Aquarium. It's not like a normal clock: it just tells you how many hours before or after high tide it is. In this case it was 3 hours after high tide. One other difference to a normal clock is that it takes more than 12 hours to go round once. Tides are caused by the Moon, which doesn't stay still. It moves on every day so there will be about 12 hours 25 minutes between two high tides.