Port-Marie, located in the Chausey archipelago, features a combination of reef and seagrass habitats. The site is suitable for beginners and offers a shallow average depth of 3 metres, with a total range between 1 and 5 metres. Access is via the shore, though the site is situated 17,000 metres from the mainland. Divers and snorkellers should be aware of strong currents present in the area. Visibility typically ranges from 10 to 20 metres. Water temperatures fluctuate throughout the year, peaking at 19°C in late summer and dropping to 9°C in late winter. Toilets are available at the site.

The Walter is a wreck dive located off Saint-Malo, resting at depths between 30 and 38 metres. This site is suited for intermediate divers who possess both Open Water and wreck qualifications. Divers access the wreck by boat, encountering moderate currents that can strengthen during ascent and descent. Visibility typically ranges from 5 to 10 metres, requiring careful navigation around the structure. Water temperatures are cold, fluctuating between 9 and 15 degrees Celsius throughout the year, necessitating appropriate thermal protection. Due to the depth and potential for entanglement in wreckage components, precise buoyancy control and the use of a cutting tool are essential safety practices for all visitors.

The Hinrich is a wreck dive located off Saint-Malo, France, resting at depths between 23 and 41 metres. This site is suited for intermediate divers due to the depth and the presence of moderate currents that can strengthen quickly. Visibility typically ranges from 5 to 10 metres, requiring methodical navigation through the structure. Given the water temperatures of 9 to 15 degrees Celsius, a drysuit or thick wetsuit is necessary. Access is by boat only. Divers should monitor depth gauges closely, manage potential entanglement risks, and use a surface marker buoy for a controlled ascent due to local boat traffic.

Plongeoir de Granville is an artificial reef located off the coast of Brittany and Normandy, France. The site features depths ranging from 5 to 18 metres, with an average depth of 12 metres. Divers must access this location by boat, as strong currents and surf conditions make shore entry hazardous. Visibility is variable, typically between 3 and 10 metres. Water temperatures fluctuate between 9 and 17 degrees Celsius, requiring appropriate thermal protection. The site is suitable for intermediate divers who can manage technically demanding conditions. Night diving is permitted, offering an alternative perspective of the artificial structure. Local facilities provide equipment rental and boat charters for site access.

Havre de Rothéneuf is a protected natural harbour in Saint-Malo, offering a sheltered environment that remains calm even when conditions in the open sea are rough. The site features a sandy bottom interspersed with rocky patches, making it a suitable location for beginners and families to snorkel from the shore. Water temperatures vary seasonally, ranging from 9C in February to 19C in August and September. Facilities available at the site include toilets and a rinse station. Species recorded around this area include European Common Cuttlefish, catsharks, sea slugs, squat lobsters, wrasses, conger eels, common lobsters, spiny spider crabs, and various sea stars.

Les Jardins de la Conchée is a boat-access site situated 4000 metres from the shore of Saint-Malo. The underwater topography features a complex environment of granite boulders and kelp gardens, alongside a wall, drop-off, and artificial reef structures. Divers can explore a wreck located within the site. Depths range from 4 to 25 metres, with an average depth of 20 metres. Conditions are variable, characterised by strong currents, surge, and surf, which require careful planning. Hazards include potential entanglement, boat traffic, and low visibility. This site is suitable for beginners, though the challenging currents necessitate caution.

Le Fetlar is a reef dive located off the coast of Saint-Malo, France. The site features a seabed ranging from 17 to 28 metres in depth. Divers should expect moderate currents throughout the area, requiring the ability to fin against the flow in short bursts. Visibility at the site typically ranges between 5 and 10 metres. Due to water temperatures fluctuating between 9 and 16 degrees Celsius, a 7mm wetsuit or a drysuit is recommended for comfort. Access to this site is exclusively by boat. It is suitable for divers seeking an introduction to temperate reef environments.

Located 3500 metres from the coast of Saint-Malo, the South Beach of Île de Cézembre is a reef site accessible only by boat. The area features rocky outcroppings and shallow waters ranging from 2 to 8 metres, with an average depth of 5 metres. This site is suitable for beginners and offers a snorkel rating of 4 out of 5. Divers and snorkellers should be aware of moderate currents and boat traffic in the vicinity. Water temperatures fluctuate between 9C in February and 18C in August and September. Facilities on the island include a cafe and toilets.