Tides
Tides have an important influence on island life, determining whether deliveries can be made between the islands and whether people can travel to work on other islands. As a visitor you will find the tide also influences your activities, for instance, how long you will visit other islands for the day as the tide will alter the boat schedules and whether you get dropped off at a main quay or whether you get dropped on a beach (and sometimes have to paddle ashore!). During big Spring Tides, the channel between the islands can become almost dry and it is possible to walk between Tresco and Bryher (but check the boat time for your return unless you fancy a swim!).
Other great opportunities for walks when the tide is low are from St.Agnes to Gugh on the sand bar, Pelistry Bay to Toll’s island on St.Mary’s and from St.Martins to White Island (this is quite rocky and seaweed grows over the rocks so suitable for the more intrepid walker!). Tides also affect any other water based activity you may wish to pursue such as fishing, kayaking, sailing, motor boat hire, windsurfing and diving.
You'll find a tide table in almost every household, most guesthouses and hotels will display them, or you can buy them locally.
Spring and Neap tides
Spring and Neap tides are created by the relationship between the Earth and the Moon during each lunar month. Spring tides occur shortly after New and Full Moon, and Neap tides occur shortly after the Moon is in its First and Third Quarter. Spring tides occur when the gravitational forces of the Sun and Moon reinforce each other resulting in a higher than normal tidal range. Neap tides occur when these gravitational forces act at right angles to each other resulting in a lower than normal tidal range. Spring Tides have a rise and fall of upto 20 feet in Scilly and about 8 feet on a Neap Tide.