In 1716 the Duchess Anne established a harbour in Lamlash. She also introduced coal mining and a salt industry to Arran. This quay was subsequently (wholly or partially) used as a quarry in about 1800 for house building in Lamlash. The present structure was presumably erected soon after. (https://portal.historicenvironment.scot/designation/LB13449).
This pier was later used as a passenger ferry terminal for steamboats from 1883 until 1954.
In 1956 Arran Yacht Club was formed to promote the sport of sailing on the Isle of Arran, based at Lamlash Pier. Later Arran Coastal Rowing Club and Arran Kayak Club were established too.
Nowadays in the season a regular boat goes from this marina to Holy Isle. Obviously, the pier is also used by private yachts, fishing boats and kayaks. This spot is particularly busy in the summer sunny days, when local kids jump from the end of the pier.