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 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.

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.

Ynys Moelfre is a reef site located 1000 metres offshore in Pembrokeshire, United Kingdom. The reef reaches depths of 10 to 18 metres, with an average depth of 14 metres. Divers encounter strong currents, making it suitable for intermediate skill levels; planning dives around slack water is essential. Visibility typically ranges from 5 to 10 metres. Marine life recorded at the site includes curled octopus, grey seals, squat lobsters, various crabs, brittle stars, common sea stars, and dead man's fingers. Water temperatures fluctuate between 8C and 16C throughout the year. Boat access is required to reach the site, and local facilities include parking, toilets, showers, and a dive shop.

Vivian Quarry is a flooded slate quarry in North Wales offering a contained, current-free dive within an industrial setting. The site features submerged quarry walls and artificial reef structures, with depths ranging from 6 to 19 metres. Visibility typically varies between 5 and 10 metres. Due to the overhead environment created by the quarry walls and potential swim-throughs, buoyancy control is essential. The water remains cold throughout the year, making a dry suit, hood, and gloves recommended. The site is suitable for beginners and supports night diving. On-site facilities include changing rooms, air fills, equipment rental, parking, and toilets, providing a convenient location for training and gear checks.

The Chacabuco is a wreck located off the coast of Pembrokeshire, United Kingdom, resting at depths between 30 and 35 metres. This site is strictly for experienced divers due to the depth, potential for nitrogen narcosis, and strong currents. Visibility at the wreck typically ranges from 5 to 15 metres. Access is exclusively by boat, and divers must time their descent around slack water to ensure the site is manageable. Given the depth and the nature of the wreck, precise buoyancy control is essential. Divers should be prepared for cold water temperatures, which fluctuate between 8C and 16C throughout the year.

Hilbre Island is the largest of three tidal islands situated in the Dee Estuary. Snorkelling is best conducted around the old lifeboat slipway during high tide, where the rocky seabed provides a habitat for various temperate marine life. The site is suited for intermediate snorkellers who can manage shore entries in variable conditions. Water temperatures fluctuate throughout the year, ranging from 7C in winter to 18C in late summer. The environment supports a variety of temperate marine life, including crustaceans and small fish typical of this coastal habitat. Visitors should be aware of the tidal nature of the island when planning their visit.

The SS Dakota is a shipwreck located 1609 metres off the coast of Pembrokeshire, United Kingdom. Resting at depths between 10 and 20 metres, with an average depth of 15 metres, the site is suitable for intermediate divers. Access is by boat only. Divers should expect strong currents and limited visibility, typically around 5 metres, making the use of a torch recommended for viewing structural details. Planning dives around slack water is essential to manage the current. Surface intervals require vigilance due to boat traffic, and caution is advised when moving near any sharp rock formations in the area.