Île Molène near Trébeurden is a reef site accessible only by boat. The location is suited for advanced divers due to the presence of strong currents. Water temperatures range from 10C in March to 17C in August and September. Species recorded around this area include European common cuttlefish, wrasses, tompot blenny, soft coral, various crab species, cod, sea stars, spirograph, snails, sea squirts, and shanny. Facilities available in the region include dive shops providing air fills, equipment rental, and guided tours. The site is also rated for snorkelling.

Roche aux Serpents is an offshore rock formation located 500 metres from the shore near Saint-Malo. The site features a topography of deep gullies and swim-throughs, supporting a kelp forest environment. Divers and snorkellers can expect depths ranging from 5 to 18 metres, with an average depth of 4 metres. Access to the site is by boat only. Conditions include moderate currents and water temperatures typically between 10C and 14C, though seasonal variations may occur. The site is suitable for intermediate divers and offers a snorkel rating of 4 out of 5. Guided tours and local dive shop support are available for those visiting this area.

Crique du Squeouel is a small creek located north of the port in Saint-Malo, France. The site features rocky walls that descend into sandy bottoms, providing a sheltered environment for snorkelling. Access is via the shore, and the site is best suited for intermediate snorkellers due to the variable conditions of the region. Water temperatures fluctuate between 10C and 17C throughout the year. Species recorded around this area include wrasses, European common cuttlefish, tompot blennies, sea stars, various crab species, soft corals, cod, spirographs, snails, sea squirts, and shannies.

Molaine is a marine dive site located off the coast of Saint-Malo, France. The site features a consistent depth of 10 metres. Water temperatures in this area fluctuate throughout the year, ranging from 10C in March to 16C during the peak months of August and September. Due to the variable nature of the local marine environment, conditions at this site can change. It is suitable for divers looking for a shallow, consistent depth profile in the Brittany and Normandy region.

Le Henry R James is a boat-accessed dive site located off Saint-Malo, France. The site features depths ranging from 40 to 50 metres, making it suitable for experienced divers. Conditions are variable, with moderate currents and visibility typically ranging between 10 and 30 metres. Water temperatures remain cool throughout the year, fluctuating between 10C and 13C. Species recorded around this area include wrasses, squat lobsters, sea hares, soft corals, crabs, spiny spider crabs, brittle stars, snails, and rockpool prawns. Divers should be prepared for deep-water conditions and the specific environmental challenges associated with this region.

Baie des Pirates in Saint-Malo is a sheltered bay frequently utilised for snorkelling initiations. The site features shallow rocky reefs that provide a habitat for juvenile fish and various Atlantic algae. With water temperatures ranging from 10C to 17C throughout the year, the site is suitable for beginners. Access to the water is available from both the shore and by boat. Conditions at this location are variable, and it is recommended that snorkellers remain aware of the local environment while exploring the rocky topography.

Le Castel in Saint-Malo is a protected Natural Area featuring extensive eelgrass beds and pink granite outcrops. This shore-entry site offers shallow waters starting from one metre, making it suitable for beginners and snorkellers. Conditions are generally calm with mild currents, providing a comfortable environment for exploration. Water temperatures range from 10C in March to 17C in August and September. Divers can expect typical dive durations of 45 minutes. On-site facilities include changing rooms, showers, air fills, equipment rental, and boat charter services provided by the local dive shop.

Île Milliau Passage is a submersible channel connecting the mainland to the island, offering a distinct environment of sandy patches and dense kelp forests. Located 100 metres from the shore, this site is suitable for intermediate divers and provides a high-quality snorkelling experience. Depths range from 1 to 8 metres, with an average of 4 metres. Divers should be prepared for strong currents and surf conditions. Water temperatures fluctuate between 10C and 16C, with summer peaks reaching up to 19C. Wetsuits are recommended for all activities. Access is via shore entry, and parking is available nearby for visitors.