Dorothea Quarry is a flooded slate quarry in Mid Wales, recognised as one of the deepest accessible freshwater dive sites in the United Kingdom. The site features steep quarry walls, submerged machinery, and industrial debris, creating a complex overhead environment. Depths range from 3 to 104 metres, with an average of 40 metres. Visibility is typically between 10 and 30 metres. Due to the significant thermocline, water temperatures drop from 16°C in the shallows to 4°C at depth. This site is suitable only for advanced, deep, or technical divers. Shore entry is required, and a drysuit with an appropriate undersuit is strongly recommended due to the cold water conditions.

Menai Straights is a reef and drift site located in Pembrokeshire, United Kingdom. The site features depths ranging from 5 to 18 metres, with an average depth of 13 metres. Divers and snorkellers should be prepared for strong currents and low visibility, which averages around 5 metres. Due to the challenging conditions and significant boat traffic, this site is suitable for intermediate divers. Access is available via both shore and boat entries. Facilities at the location include parking, toilets, and air fills. Typical dives last approximately 30 minutes, and night diving is permitted.

The Hoveringham Wreck is a shallow marine dive site located in Pembrokeshire, United Kingdom. Accessible only by boat, the site features a wreck lying at a depth of 3 to 10 metres. Divers should be prepared for strong currents in this area, which can impact the dive experience. Visibility is consistently recorded at 5 metres. Water temperatures fluctuate throughout the year, ranging from a low of 8C in February and March to a high of 16C during August and September. Due to the current conditions, this site is best suited for experienced divers comfortable with moving water.

Llanddwyn Island is a tidal island featuring rocky inlets and secluded coves. This shore-entry site is suited for intermediate snorkellers who can navigate moderate currents and surf. Water temperatures range from 9C to 16C, reflecting the cold conditions typical of the region. Divers and snorkellers should be aware of potential hazards including rip currents, strong currents, and low visibility. The site provides access to parking, toilets, showers, and a cafe. A typical visit lasts approximately 60 minutes. As a tidal location, the topography is best explored during high tide when the rocky inlets are fully submerged.

Puffin Island in Pembrokeshire offers a challenging marine environment featuring a mix of reef, kelp forest, and cave topography. Divers can explore depths ranging from 8 to 35 metres, with an average depth of 20 metres. Access is strictly by boat, as the site is located 800 metres from the shore. Conditions are variable, with strong currents and surge present, alongside visibility ranging from 5 to 15 metres. Due to the strong currents and potential for low visibility, this site is recommended for intermediate divers. Typical dive times are approximately 40 minutes. Divers should remain vigilant for boat traffic in the area.

The Kimya is a wreck site located in Pembrokeshire, United Kingdom, resting at depths between 10 and 15 metres. This site is suitable for beginner divers looking for a manageable wreck experience. Divers can expect mild currents and visibility ranging from 5 to 10 metres. Access to the site is strictly by boat, as the water edge features surf and shore breaks. Water temperatures fluctuate between 9 and 16 degrees Celsius, necessitating the use of a drysuit or thick wetsuit. Boat traffic is a primary hazard, so divers should deploy an SMB upon ascent and remain close to their guide or charter crew.

Criccieth Castle is a shallow shore dive featuring reef structures that provide a navigation challenge for divers. The site typically ranges from 5 to 8 metres in depth, though it extends to 30 metres in some areas. Conditions are characterised by mild currents and variable visibility, which can occasionally be very low. Divers should be prepared for water temperatures between 8C and 18C. Due to the risk of boat traffic, the use of a surface marker buoy is essential throughout the dive. Parking is available at the site, facilitating a straightforward shore entry for those looking to build experience in temperate marine environments.

Trefor Pier is an artificial reef site located in Pembrokeshire, United Kingdom. Divers can explore the structure at depths ranging from 2 to 8 metres, with an average depth of 6 metres. This shore entry site is suitable for beginners and offers mild currents. Visibility typically ranges between 5 and 10 metres. The site is accessible for night diving, with a typical dive duration of 60 minutes. Facilities available at the location include parking, toilets, air fills, and a cafe. Divers should remain aware of potential hazards, including boat traffic, entanglement risks, and surf conditions. Water temperatures fluctuate between 8C and 17C throughout the year.