Fort Boyard is a fort located between the Île-d'Aix and the Île d'Oléron in the Pertuis d'Antioche straits, on the west coast of France.

Fort Louvois, also known as Fort du Chapus, is a maritime stronghold off the western coast of France.

The îles Saint-Marcouf is a group of small islands off the coast of Normandy.

Bréhon Tower is an imposing sea fortification situated on a rocky islet.

The Nab Tower is a tower planned for anti-submarine protection in the Solent, at a point around 6 miles east of the entrance to Portsmouth harbour, England.

St Helens Fort is a distinctive sea fort located near the Isle of Wight.

No Man's Land Fort is a sea fort located in the Solent, near the coast of the Isle of Wight, England.

Horse Sand Fort is one of the largest sea forts in the Solent, off Portsmouth, England.