The Dives Worth Making the Journey For

Chesil Cove

Start here if it’s your first visit. One of the best shore dives (if there is an easterly wind) on the south coast, with good marine life, easy access from the beach, and the option to go back at night for a completely different experience. No boat, no complicated logistics — get in and explore.

The Countess of Erne

A solid first boat dive for newer divers. This Victorian paddle steamer, later converted to a coal hulk, broke her moorings in 1935 and sank against the breakwater. She lies upright at around 14 metres — shallow, largely intact, and a proper wreck dive without the pressure of depth. Go early in the day before other divers stir up the silt.

The Aeolian Sky

A large Greek-registered freighter lying on her port side at around 28–30 metres on a limestone seabed. She’s a big wreck — a 40-minute dive won’t get you around more than a fraction of her — and she holds a lot of fish life. Best suited to Advanced Open Water divers and above.

The M2 Submarine

This is the one. The M2 is Portland’s headline act and one of the most talked-about wreck dives in the country. Built as a conventional submarine after the First World War, she was later converted into something unique — a submarine aircraft carrier, fitted with a watertight hangar and a small seaplane that could be launched by catapult from the deck. She sank in January 1932 during exercises off Portland, almost certainly because the hangar door was opened while she was still surfacing. All 60 crew were lost. After nearly a year of salvage attempts the Admiralty gave up, and she’s been on the seabed ever since. She’s a designated war grave and should be treated as such.

She sits upright at around 32 metres, largely intact, with the hangar, catapult tracks, and bow all clearly identifiable. You’ll need at minimum an Advanced Open Water qualification and ideally a Deep Diver speciality. Timing around slack water is essential — get it wrong and you won’t get down. Get it right and it’s one of those dives you’ll still be talking about on the drive home.

Drift Diving

The tidal flow around Portland Bill generates some of the best drift diving in the country. Sites like Bottlebank, Balaclava Bay, and the Blacknor wall are all worth adding to your itinerary. Plan carefully around the tides and it’s exhilarating; ignore them and it’s a very different story.

What You’ll See

The reefs and ledges on Portland’s east side hold lobsters, blennies, and plenty of life to find among the kelp. The wrecks attract conger eels, large shoals of bib, nudibranchs, and the occasional cuttlefish. Scallops turn up regularly on sandy patches between sites. Visibility is variable — 2 metres on a poor day, 8–10 metres when conditions are favourable — with late spring and summer generally the most reliable window.

The Operators

There are several good operators running boats out of Portland Marina and Castletown, and between them they cover everything from shuttle dives for individuals to full day charters for clubs and groups.

Skin Deeper and the Portland Gas Shack are run together out of Portland Marina and have been a fixture of the Portland diving scene for nearly two decades. Skin Deeper operates a purpose-built catamaran certified for up to 12 divers, covering everything from inshore harbour dives to offshore wrecks and technical sites. The Gas Shack side of the operation handles cylinder fills including nitrox and trimix to 300 bar — making them a one-stop shop whether you’re diving recreational air or planning something more technical. Between the two, they’re one of the most useful contacts to have sorted before you arrive.

Scimitar Diving and Jurassic Aquasports also run regular charters and shuttles from Portland Marina, covering wrecks, reefs, and drift dives across the Dorset coast.

Portland is home to O’Three, one of the UK’s leading drysuit manufacturers. Their suits are designed and built locally, shaped by the exact conditions divers experience here, cold water, variable visibility, and demanding shore entries. O’Three has developed a reputation as a market leader in neoprene drysuit design, with a strong focus on durability, fit, and thermal performance.

Having a manufacturer of this calibre based in Portland isn’t accidental, it reflects just how important this stretch of coastline is for real-world UK diving.

Just across from O’Three, you’ll find Underwater Explorers, one of the UK’s best-known dive equipment centres. Based near Portland Marina, they stock a wide range of cutting-edge gear and serve everyone from recreational divers to technical explorers.

Big Squid in Portland

We’ve recently opened a dive shop in Portland, so if you’re making the trip down, you can now get kitted out, pick up anything you’ve forgotten, or sort equipment with a familiar face. It also means Big Squid members have a direct connection between London and one of the UK’s best dive destinations — training in Clapham, diving at Portland, with the same team behind both ends of the journey. More details on the shop here.

Making the Trip

Portland is around three hours from London, close enough for a long weekend, far enough to feel like a proper dive trip. Boats fill quickly from April through September, so book ahead, particularly for popular sites like the M2. A drysuit is the right call year-round, with water temperatures ranging from around 8°C in winter to 17°C at the summer peak.

If you’re not yet at Advanced Open Water level, it’s worth getting that sorted before you go; it opens up the M2, the Aeolian Sky, and most of the deeper drift sites and makes the whole trip significantly more rewarding. Big Squid runs Advanced Open Water courses in London throughout the year, with confined water sessions in Clapham and open water dives at Vobster.

It’s a proper dive destination on your doorstep. Worth every mile of the drive.

Frequently Asked Questions

Is Portland good for beginner divers? Yes, though it depends on the sites you choose. Portland Harbour has several sheltered, shallow wrecks that are well suited to newly qualified divers, and Chesil Cove is an excellent shore dive at manageable depths. More demanding sites like the M2 require Advanced Open Water as a minimum, so it’s worth having that qualification in place before you go if you want to make the most of what’s on offer.

What qualification do I need to dive the M2 submarine? You’ll need at minimum a PADI Advanced Open Water or equivalent, and ideally a Deep Diver speciality, as the wreck sits at around 32 metres. Some operators will also specify a minimum number of logged dives. The M2 is a designated war grave, so all visits should be conducted with appropriate care and respect.

How far is Portland from London? Portland is roughly three and a half hours from central London by car, making it a very manageable journey for a weekend trip. The most straightforward route is via the A303 through Wiltshire and Dorset.

When is the best time of year to dive Portland? Diving is possible year-round thanks to the sheltered nature of Portland Harbour, but visibility and conditions outside the harbour are generally at their best from late April through to September. Boat spaces on popular sites fill up quickly over summer weekends, so booking ahead is strongly recommended.

Do I need a drysuit to dive Portland? A drysuit is the sensible choice for Portland year-round. Water temperatures typically range from around 8°C in winter to 17°C at the peak of summer, manageable in a thick wetsuit during the warmer months, but a drysuit will make every dive more comfortable and extend your season considerably. If you’re not yet drysuit qualified, Big Squid run a Drysuit Diver course in London that’s worth doing before your first Portland trip.

Can I get air and nitrox fills at Portland? Yes. The Portland Gas Shack at Portland Marina offers a full gas filling service including air, nitrox, and trimix to 300 bar. Most of the boat operators can also arrange fills as part of your booking.

Do I need to bring all my own equipment? Most operators offer kit hire if you don’t have your own, and Big Squid’s dive shop in Portland means you can pick up anything you’ve forgotten or need on the day. It’s always worth confirming equipment availability when you book your boat.

Can Big Squid help me plan a Portland dive trip? Yes — get in touch, and we can point you in the right direction for operators, sites suited to your experience level, and anything you need to sort beforehand, whether that’s an Advanced Open Water course, a Drysuit qualification, or just some advice on what to expect. Contact us here.