Forme 4 is a unique flooded dry dock located within the port of Dunkerque, France. This site functions as a sheltered seawater pool, providing a controlled environment for snorkelling that is distinct from the open sea. The topography features submerged industrial relics, offering an unusual underwater landscape. Water temperatures vary significantly throughout the year, ranging from 8C in late winter to 19C in late summer. Due to its protected nature, the site is suitable for beginners. The habitat supports a variety of temperate marine life, including various crustaceans, cephalopods, and bottom-dwelling fish species typical of the region.

The Foudroyant is a shipwreck located off the coast of Dunkerque, France. Resting at depths between 24 and 30 metres, this site requires boat access and is suited for intermediate divers. Conditions are characterised by mild currents and visibility ranging from 5 to 15 metres. Divers should be prepared for variable swell and surge, which can impact the wreck's interior. Due to the overhead environment and potential for entanglement, careful buoyancy control is essential. A torch and reel are recommended for navigation. Water temperatures fluctuate between 8 and 16 degrees Celsius throughout the year, making a drysuit or thick wetsuit appropriate for the typical 40-minute dive duration.

The SS Trifels is a deep-water wreck located off the coast of Dunkerque, France. Resting at depths between 10 and 36 metres, this site is suited for advanced divers. The wreck features a complex overhead environment with numerous swim-throughs, requiring careful navigation and buoyancy control. Divers must be prepared for moderate currents and visibility ranging from 3 to 10 metres. Due to the presence of sharp surfaces and entanglement risks, a wreck reel and redundant cutting tools are essential. Water temperatures are cool, fluctuating between 8 and 16 degrees Celsius throughout the year, making a drysuit the recommended equipment for this dive.

The Paris SS is a shipwreck located off the coast of Dunkerque, France. Resting at depths between 30 and 35 metres, this site is suited for intermediate divers. Access is exclusively by boat, and the environment requires careful buoyancy management due to the depth and potential surge around the structure. Visibility varies from 5 to 15 metres, and water temperatures range from 9C to 15C, making a drysuit or thick wetsuit necessary. Divers should remain aware of swell conditions during entry and ascent. The wreck features an encrusted character across its hull and metalwork, providing a complex structure to navigate.

The John Mahn is a wreck site located 37 kilometres from shore, functioning as an artificial reef. Divers encounter depths ranging from 21 to 35 metres, requiring careful management of decompression limits and nitrogen narcosis. Conditions include moderate currents and visibility between 5 and 10 metres, often necessitating the use of a torch. Water temperatures fluctuate between 8 and 19 degrees Celsius, making a drysuit essential for most of the year. Due to the depth and potential for entanglement, this site is suited for intermediate divers. Access is strictly by boat, and conditions should be monitored closely before entry.