Grotte de Boulegeade at Île de Riou offers a diverse underwater experience combining a cave system, reef, wall, and drift diving. Depths range from 7 to 45 metres, with an average of 28 metres. Divers encounter moderate currents, particularly near the cave entrance. Visibility typically spans 15 to 25 metres. Marine life includes wrasses, scorpionfish, common octopus, Mediterranean moray, and various nudibranchs such as the tricolor doris and cratena slug. Due to the overhead environment and depth, this site is suited for intermediate divers with appropriate training. Access is by boat only, and a torch is recommended for navigating the cave interior where natural light diminishes rapidly.

Les Moyades, located at Île de Riou, offers a diverse underwater topography consisting of reefs, walls, and caves. Divers can explore depths ranging from 3 to 35 metres, with an average depth of 20 metres. The site requires boat access and is suitable for intermediate divers. Visibility typically spans 10 to 30 metres. Marine life includes common sightings of wrasses and scorpionfish, while uncommon species such as common octopus, great barracuda, Mediterranean moray, and various nudibranchs are also recorded. Hazards include sea urchins, sharp rocks, and overhead environments in cave sections. Water temperatures range from 14 to 18C, necessitating appropriate thermal protection. Night diving is available at this location.

Iles des Moyades is a marine site located at Île de Riou, featuring a varied topography of reefs, walls, and canyons. The site reaches depths between 5 and 45 metres and is accessible only by boat. Divers and snorkellers can expect mild currents and visibility ranging from 10 to 25 metres. Water temperatures fluctuate between 13C and 18C throughout the year. Due to the presence of surf, appropriate caution is advised during entry and exit. Typical dives at this location last approximately 45 minutes.

Les Moyadons is a wall and reef site located off the Île de Riou. The topography features a wall dropping to a maximum depth of 37 metres, with shallower reef sections starting above 10 metres. Divers can expect visibility ranging from 10 to 30 metres. This site requires boat access and is suited for intermediate divers due to moderate currents that can strengthen without warning. Water temperatures fluctuate between 14C and 19C throughout the year. Divers should exercise caution to avoid contact with sharp coral and rock edges along the wall. Planning dives to work against the current during the initial phase is recommended.

Les Pierres Tombées, located off the Île de Riou, features a combination of reef and drop-off topography. The site ranges from 15 to 29 metres in depth, with an average of 20 metres. Divers can explore shallower reef sections before reaching the deeper edge. Visibility typically spans 10 to 30 metres. The site is suitable for beginners, though a moderate current requires careful buoyancy management. Marine life includes common scorpionfish and various wrasses, alongside less frequent sightings of Mediterranean moray, great barracuda, common octopus, and several species of nudibranchs and flatworms. Boat access is required, and a 5 mm wetsuit is recommended due to water temperatures between 14 and 18 degrees Celsius.

Le Couloir aux gorgones is a boat-access reef located off the Île de Riou near Marseille. The site features depths ranging from 25 to 36 metres, requiring appropriate depth certification and buoyancy control. Divers typically encounter moderate currents, making it necessary to plan dive profiles carefully and utilise the reef for shelter. Visibility at the site varies between 10 and 30 metres depending on local conditions. Water temperatures fluctuate between 13 and 19 degrees Celsius throughout the year, necessitating a thick wetsuit or drysuit for thermal protection. Given the depth and current, this site is best suited for experienced divers.

Les Deux Jumelles is a deep reef and wall site located off the Île de Riou. The topography consists of a steep wall dropping to depths between 57 and 65 metres, with an average depth of 61 metres. This site is strictly for advanced divers with deep diving certifications, as the depth presents the primary hazard. Conditions include mild currents and visibility ranging from 5 to 10 metres. Due to the significant depth and water temperatures between 13 and 18 degrees Celsius, a drysuit or thick wetsuit with hood and gloves is recommended. Boat access is required, and guided tours are available locally to assist with navigation and safety.

Calanque de Monasterio is a remote reef site located on the uninhabited Île de Riou. Accessible only by boat, this location features white sandy bottoms and is situated within the National Park. The site is suitable for intermediate snorkellers, offering a 5/5 rating for the activity. Water temperatures fluctuate throughout the year, ranging from 14C in the winter months to 24C in August. Due to its distance from the shore, approximately 14 kilometres, visitors should be prepared for moderate currents. The site provides a quiet environment for observing the underwater topography of the Riou Archipelago.