Cramond Island is a tidal island about one mile (1.6 km) out to sea, which is connected to the mainland at low tide across the Drum Sands. A paved path, exposed at low water, allows easy access. This causeway runs at the foot of a row of concrete pylons on one side of the causeway, which were constructed as an anti-boat boom during the Second World War and are one of the most striking sights in the area. At high tide the path is covered by several feet of seawater which cuts the island off from the mainland. It is safe to walk along the raised causeway to the island at low tide, but only if visitors ensure that they leave enough time to return to the mainland before the water rises. The speed at which the tide comes in can easily trap the unwary. A large signpost (located at the start of the causeway) warns visitors of the danger. If this warning is ignored, there can be serious accidents or people may be stranded on the island until the next low tide. In 2011, a Daniel Defoe of Livingston, West Lothian and an unidentified female found themselves trapped on the island due to miscalculating the times of the tide. This story gained attention due to the ironic parallels with Robinson Crusoe; a novel written by Daniel Defoe published in 1719. Coastguards recommend that the crossing is only attempted during the two hours either side of low water. On the RNLI (Royal National Lifeboat Institute) Queensferry website there is a list of “safe crossing times” and it states that the “times are given as a guide and may change due to weather and conditions. Times listed in WHITE are the first safe crossing time and those listed in RED are when to be back on the mainland”.