Porth Diana & Porth CastellTrearddur Bay, Anglesey

Porth Diana and Porth Castell, Trearddur Bay, Anglesey

Porth Diana and Porth Castell are part of a series of smaller bays and coves that flank both sides of the main beach in Trearddur Bay. At only
2.02 hectares, Porth Diana is the smallest nature reserve on Anglesey, and committed to protecting our county flower, the beautiful Spotted Rock Rose! You’ll often find some welcome shelter in these pretty little coves.  

Both bays are surrounded by rocks, made up of of mica-schist, and backed by a sea wall. Being far more protected than the main beach of Trearddur Bay, Porth Diana, especially, is used for mooring boats, especially those owned by members of the Trearddur Bay Sailing Club. Porth Castell, just to the south, is possibly the better bay for swimming. Both Porth Diana and Porth Castell, are great for family picnics. There’s ample opportunity for swimming, building sandcastles, climbing, exploring and rockpooling too!


With the surrounding coastline being so abundant in marine life and awash with wrecks and reefs, both bays are commonly used as a starting point for scuba divers. There’s even a dedicated dive shop just behind them.

At a glance
  • Great beaches for family picnics.

  • Crystal clear waters - renowned as scuba diving starting points.

  • The smallest nature reserve on Anglesey - committed to protecting the beautiful Spotted Rock Rose.

  • Great for rockpooling and exploring.

  • Wonderful for watersports - including kayaking, swimming and sailing.

Beach info

Beach type



There are toilets in the car park and the ice cream van is often parked there in season.


Parking is at the pay and display car park, from which there runs a tarmac path for about 400m to the beach. There are disabled bays available in the car park itself.


There is disabled parking available and access to the beach is a 400m tarmac footpath which crosses the dunes and takes you to the beach. This makes access easy for those using a wheelchair or families with a pushchair.

Dog restrictions

Dog restrictions apply to the north of the main access point for a distance of about 500 yards and run from April 1st until September 30th.

Top tips
Flora & Fauna
Weather & tide

The whole of this coast is popular with anglers. You’ll often see people fishing off the beach here, as well as from the rocks and ledges in the surrounding area. The cliffs at Ravenspoint are a great place to catch congers, codling, pollock, wrasse and dogfish - and all the usual suspects! Mackerel fishing, offshore, can be super here during the summer months.


You are responsible for your own safety when visiting a suggested beach. We make no representations or warranties as to the accuracy of the information on this site in relation to any of the suggested beaches. While we try to ensure that all beaches on this site are suitable for the purpose for which they are suggested, you should be aware that no beach is entirely safe and all beaches carry a degree of risk to person and property. It is your responsibility to ensure that you mitigate any such inherent risks.

We accept no responsibility for loss or damage to personal effects, personal accident, injury or public liability in relation to a suggested beach on this site (although we do not exclude or limit in any way our liability to you where it would be unlawful to do so). Furthermore, while we try to ensure that all suggested beaches are open to the public, this is liable to change and you should ensure that this is the case before you visit. Please respect private property (including livestock), as we accept no responsibility for trespassing or damage to private property, to either you or any third party. Please take extra care around steep drops on cliff paths. Water quality may vary and be aware that some beaches may not allow dogs.

Always follow advice from relevant authorities, including HM Coastguard and any lifeguards present on the beach. Swimming flags must always be adhered to. Currents can be strong enough to drag even a strong swimmer, and rocks and unexpected shallow or deep water may not always be obvious. Swimming should only be done in calm conditions when supervised from land, ideally by a lifeguard on a flagged beach. Avoid swimming around boats, jet skis or surfers. Check the weather forecast and tide timetables in advance of a visit to a beach. Always pack water and appropriate clothing. Be aware of the risk of sunburn and wear a high-factor sun-cream. Children and pets should be supervised at all times, and dogs should be kept on a lead.

The contents of this site is provided for general information only. It is not intended to amount to advice on which you should rely. Where this site contains links to other sites and resources provided by third parties, these links are provided for your information only. Such links should not be interpreted as approval by us of those linked websites or information you may obtain from them. We have no control over the contents of those sites or resources.

If you do find any errors relating to any of our suggested beaches, we would be grateful if you would let us know by emailing us at explore@menaiholidays.co.uk

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