Robertson's Yard at Sandbank, a village on the loch, was a major wooden boat building company in the late 19th and early 20th centuries.

Dunoon on the Cowal peninsula lies on the shores of the Clyde just to the south of the loch, and houses continue round the villages of Kirn, Hunters Quay, Ardnadam and past Lazaretto Point, the village of Sandbank, with open countryside at the end of the loch, then on the northern shore Kilmun, and at Strone Point the village of Strone continues on the western shore of the Firth of Clyde, almost joining Blairmore on Loch Long.

More than 55 boats were built by Robertsons in preparation for the First World War and the yard remained busy even during the Great Depression in the 1930s, as many wealthy businessmen developed a passion for yacht racing.

During World War II the yard was devoted to Admiralty work, producing a wide range of large high speed Fairmile Marine Motor Boats (MTBs and MGBs).

After the war the yard built the successful one-class Loch Longs and two 12-metre challengers for the America's Cup: Sceptre (1958) (17 tonnes) and Sovereign (1964).

During World War II the loch was used by the Royal Navy as a submarine base, served by the depot ship HMS Forth.

Near the Holy Loch an anti-submarine boom was constructed between Dunoon and the Cloch Point Lighthouse to defend waters from German U-boats.

To make maximum use of its submarine-launched ballistic missile (SLBM) force, the American military had determined that it required an overseas base for refit and crew turnover.

Site selection criteria included the requirements for a sheltered anchorage, relative proximity to an international airport, and sufficient shore facilities to provide housing for military personnel and their families.

Agreement for the use of Holy Loch was reached near the end of 1960 and the arrival of the first tender, USS Proteus (AS-19) scheduled for December.

Divisions within the British government and concerns about protests by the Campaign for Nuclear Disarmament (CND) caused her arrival to be rescheduled to 3 March 1961.

In 1982, Naval Support Activity (NAVSUPPACT), Forward Base, Holy Loch, Scotland became its own command.