Portland offers a diverse range of marine environments including wrecks, reefs, and drift sites located off the South Coast of England. Divers can explore depths ranging from 5 to 30 metres, with an average depth of 28 metres. Access to these sites is strictly by boat, as they are situated approximately 100 metres from the shore. Conditions are variable, with visibility fluctuating between 1 and 20 metres and strong currents present. Due to the challenging nature of the currents and potential for entanglement, this site is best suited for intermediate divers. Water temperatures range from 9C to 18C throughout the year, necessitating appropriate thermal protection.

Portland Harbour offers a diverse underwater environment featuring a mix of natural reefs, wrecks, and artificial reef structures. Depths range from 2 to 14 metres, with an average of 10 metres, making it suitable for beginners. Divers can access the site via boat or shore. Visibility varies between 2 and 10 metres, and currents are generally mild. The site supports night diving and provides comprehensive facilities including showers, rinse stations, and air fills. Due to significant boat traffic, divers must tow a surface marker buoy at all times and remain vigilant during ascents. Always check harbour authority notices before entering the water.

Chesil Beach offers a shore-entry dive featuring a mix of reef and wreck topography. Depths range from 3 to 18 metres, with an average of 8 metres. Conditions are variable, with visibility ranging between 1 and 10 metres and mild currents. Divers should be aware of potential hazards including entanglement, rip currents, strong currents, surf, and surge. Water temperatures fluctuate between 9C and 18C, presenting a risk of hypothermia. Species recorded around this area include European Common Cuttlefish, Gray Seal, wrasses, brittle stars, spiny spider crabs, sea stars, snails, triplefins, European green crabs, and sea squirts. Facilities at the site include parking, toilets, and a cafe. Night diving is possible.

The Gertrude Wreck is a combined wreck and reef site located off the South Coast of England. Resting at depths between 6 and 14 metres, the site is suitable for intermediate divers. Access is by boat, which is required due to its distance of 2450 metres from the shore. Divers can expect mild currents, though these may strengthen, and visibility typically ranges from 5 to 15 metres. Water temperatures fluctuate between 9 and 18C throughout the year. Due to the wreck structure, there is a risk of entanglement, and divers should carry a line cutter. Species recorded around this area include European Common Cuttlefish, Gray Seal, wrasses, and various crustaceans.

The James Fennel Wreck is a boat-accessible dive site located 1000 metres off the coast of Swanage and Poole. This wreck and reef site sits at an average depth of 15 metres, with a total depth range between 14 and 18 metres. Divers can expect mild currents and visibility ranging from 5 to 30 metres. The site is suitable for beginners and typically offers a 45-minute dive duration. Facilities available in the area include parking, toilets, showers, changing rooms, air fills, dive shops, boat charters, and guided tours. Water temperatures fluctuate seasonally between 9C and 18C.

Durdle Door is a geological landmark featuring a natural arch, rocky gullies, and a small cavern on the Man O War side. Divers can explore depths ranging from 5 to 15 metres, with an average depth of 10 metres. The site is accessible from the shore, though it requires a swim of approximately 800 metres. Conditions are variable, with strong currents, surge, and surf present. Due to the overhead environment of the cavern and potential rip currents, this site requires careful planning. Water temperatures remain cold throughout the year, ranging from 9C to 18C, necessitating appropriate thermal protection for all divers.

Man O'War Cove is a crescent-shaped bay located near Durdle Door, defined by a partially submerged offshore reef. This site is suitable for intermediate divers and snorkellers, with depths ranging from 7 to 14 metres and an average depth of 7 metres. Access is via the shore, with the reef situated approximately 100 metres out. Conditions vary, with moderate currents and visibility typically starting at 6 metres. Water temperatures fluctuate between 9C and 18C throughout the year. Facilities available at the site include parking, toilets, and a cafe. Hazards to consider include the potential for rip currents, surf, and strong currents.

Lulworth Banks is a marine site located 3200 metres from the shore near Swanage and Poole. This site features a combination of reef and wreck topography, requiring boat access for all dives. Divers can expect depths ranging between 18 and 22 metres, with an average depth of 19 metres. Conditions vary, with visibility ranging from 5 to 25 metres and moderate currents present. Due to the presence of wrecks and potential for strong currents, this site is suited for intermediate divers. Hazards include boat traffic, entanglement risks, and overhead environments. Water temperatures fluctuate seasonally between 9C and 18C.