Porth Ysgaden is a sheltered horseshoe-shaped bay on the Llŷn Peninsula, Pembrokeshire, featuring rocky walls and shallow gullies. This shore-entry site is suitable for beginners, with depths ranging from 5 to 9 metres and an average depth of 5 metres. Divers can expect mild currents and visibility between 3 and 10 metres. The site is accessible via a slipway and offers parking facilities. Night diving is possible, with typical dives lasting around 50 minutes. Water temperatures fluctuate between 9C and 16C throughout the year. Divers and snorkellers should remain aware of boat traffic and potential entanglement hazards in the area.

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.

Porth Iago is a sheltered cove on the Llŷn Peninsula, Pembrokeshire, featuring a reef environment accessible from the shore. The site is well-suited for beginners, with an average depth of 3 metres and a maximum depth of 5 metres. Snorkellers can explore the rocky edges of the cove, which provide varied micro-habitats. Conditions are generally mild, though visitors should be aware of potential surf. Facilities available at the site include parking, toilets, showers, and a cafe. Water temperatures fluctuate between 9C and 16C throughout the year.

Segontuim is a wreck dive located in Pembrokeshire, United Kingdom, resting at depths between 20 and 31 metres with an average depth of 27 metres. This site is suited for intermediate divers due to the moderate currents and entanglement hazards present on the structure. Visibility is typically limited to 5 metres, requiring careful navigation and the use of torches. Water temperatures range from 9C to 16C, necessitating appropriate thermal protection. Access is by boat only, situated 14 kilometres from the shore. The wreck provides a habitat for various temperate marine life, including reef fish and invertebrates common to the region. Guided tours and air fills are available locally.

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.

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.

Bardsey Island (Ynys Enlli) is a marine site located off the coast of North Wales, accessible exclusively by boat. The southern tip of the island features a series of inlets suitable for snorkeling. Conditions at this site vary, with water temperatures ranging from 9C in the winter months to 16C during late summer. Due to the nature of the location and the potential for variable conditions, this site is recommended for advanced snorkelers. There is no specific data regarding marine life at this location.

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.