During World War II the loch was used by the Royal Navy as a submarine base, served by the depot ship HMS Forth.
The loch was used extensively for trials and exercises by Royal Navy submarines during the war, the submarines HMS Vandal (P64) and HMS Untamed (P58)  were lost in the Clyde after being sunk by accidents during exercises.
Untamed was later salvaged.

Near the Holy Loch an anti-submarine boom was constructed between Dunoon and the Cloch Point Lighthouse to defend waters from German U-boats.
During World War II the loch was used by the Royal Navy as a submarine base, served by the depot ship HMS Forth. The loch was used extensively for trials and exercises by Royal Navy submarines during the war, the submarines HMS Vandal (P64) and HMS Untamed (P58)  were lost in the Clyde after being sunk by accidents during exercises. Untamed was later salvaged.
Near the Holy Loch an anti-submarine boom was constructed between Dunoon and the Cloch Point Lighthouse to defend waters from German U-boats.
Holy Loch