The dramatic, mountainous island of Arran provides the subject matter for the third chapter. The island lies west of the main shipping flow up and down the river, and has seen more than its fair share of shipwrecks, as vessels attempted to hug her shoreline, using the island as shelter from the prevailing west and south west winds or as they ran for shelter provided by the bays at Lamlash and Brodick. Many more were smashed to pieces on her exposed south west shore in violent storms or ran aground there in fog or at night. The exposed nature of this coastline and its attraction for shipwrecks led to the construction of the lighthouse on Pladda, the small rocky islet on the south tip of Arran, in 1790, the second lighthouse to be built on the Clyde. Despite this precaution, the shallow waters hereabouts continued to be a graveyard for many more ships over the ensuing years. The landlocked bay at Lamlash was a favourite haven for ships seeking shelter and it was not uncommon for more than a hundred ships to be anchored there in bad weather. The steep dark slopes of Holy Isle and the hills of the main island provide shelter to one of the best anchorages on the west coast of Scotland. The bay was also used by the Navy during the war. There are a number of wrecks close to the bay and around Holy Isle, and most of these are small coastal sailing vessels. The south end of Arran has the main concentration of shipwrecks. The sea here is relatively shallow and the coastline very exposed. As such, most of the wrecks are well broken and often some distance from the shore as they grounded on one of the outlying reefs. The attentions of salvage firms have further dismantled the wrecks leaving them bare, broken and often difficult to identify. The northern half of the island is characterised by steep sandy slopes descending into depths of 50-70 metres or deeper, and most wrecks here have been lost as a result of collision or foundering in open water. As a result there are a few if many within air diving range, any that have been lost in shallow water have since completely disintegrated. Diving around Arran is pleasant and easy with few complications and generally better visibility than other areas in the Clyde. The weather, which caused many of the shipwrecks, in turn proves to be the main hazard to the diver. On the exposed south west coast the prevailing winds and swell often making diving impossible or, at best, dangerous. However, the advantage of diving on an island is that it is always possible to dive somewhere, no matter how poor the weather or from which direction the wind is blowing. Boat access is surprisingly difficult but the slip at Lamlash provides access to many of the better sites.