Arnside Tidal Bore

Morecambe Bay is a large sandy bay in the north west of England and is a designated European wildlife and Ramsar site. The Bay stretches from Walney Island in the north to Fleetwood in the south, taking in the coastal resorts of Grange over Sands, Arnside and Morecambe. With regard to the AONB, approximately 40% of the designated AONB area is within the Bay and therefore covered by tidal waters twice a day!

The Arnside Bore © Adam Donaldson

The tidal bore results from a combination of the high tidal range and the shape of the bay as it narrows into the Kent Estuary at Arnside. The water enters the tapering estuary and the rising waters become confined which results in a distinct wave developing, which can be anything from a few centimetres to almost a metre high on full spring tides. 

Predicted tides of 9.5m or more are needed before it is likely that a full bore will rise and even then the bore is inconsistent and sometimes doesn't really develop at all.

They seem to be affected by the wind strength and direction, the shifting channels and sand bars and even the volume of water coming down the River Kent. 

The coastal habitats can be windswept and invigorating and (when the weather is clear) provide spectacular open views across the estuary and Morecambe Bay and into the mountains and hills of the Lake District.


These areas are characterised by areas of salt marsh and broad expanses of mud and sand flats. These form part of a shallow inlet and bay estuarine system of international importance for the conservation of wild birds and valued habitats designated both as SPA and SAC.

The mudflats provide rich feeding grounds that support large populations of wintering wading birds, including oystercatcher, dunlin, knot and wintering wildfowl including shelduck, pintail and eider, which add much to the natural beauty of the landscape.

Venturing onto the sands is extremely hazardous due to the speed of the incoming tide, the presence of quick sands and deep fast-flowing river channels. The intertidal sand and mudflats are a dynamic environment and change in form and character with every tide. Only venture onto the sands if you are sure it is safe to do so.

If you want to walk the sands, take the safe alternative by joining one of the many guided walks in the summer months. There is an official Queen's guide to the sands, who leads a considerable number of Cross Bay walks each year from Arnside to Kents Bank, as well as other led by guides from Hest Bank following the old coaching route across the bay. Walks are in aid of various charities and you can check out detail on the following link -

Bore(ing) facts:

  • The Bay is the largest continuous intertidal area in the whole of Britain, an area of 310km2
  • The Bay consists mainly of intertidal sandflats and mudflats, with few rocks or islands
  • Morecambe Bay has more than 5% of the UK's total area of saltmarsh
  • The Bay is broad and shallow with a large tidal range of up to 10.5 metres at spring tides
  • A southwesterly gale can add upto a metre to a predicted high tide, leading to coastal flooding
  • The ebbing tide can fall back 12km from the high tide shoreline in places
  • The flood tide rushes into the Bay with the speed of 'a good horse'
  • Tidal bores reach speeds of 9 - 10 knots and be almost a metre high
  • Several rivers flow into Morecambe Bay including the Kent, Keer, Leven, Lune and Wyre
  • The viaduct develops standing waves under its arches on an incoming tide which last around half an hour 
  • Experienced canoeists often "ride" the bore, which arrives about 1½ hours before highwater
  • Catching a bore from Blackstone Point gives the chance for an exciting 1½ km "surf" back to the viaduct at Arnside

Coastguard rescue jet ski

To check for the times and heights of tides visit the tide table pages at the BBC website (for Barrow Ramsden Dock) or the Admiralty Easy Tide Website linked to Arnside.

Silverdale School 701 club produced a Morecambe Bay Advice leaflet which you can download here or by clicking on the cover image on the right. The project was funded by Lancashire County Council and the AONB Sustainable Development Fund.



There is a seasonal siren signal at Arnside, provided by South Lakeland District Council, to warn of the incoming tide. The siren is sounded twice before each daylight high tide, the first time at roughly 20 minutes before the tidal bore is due. 

The second siren warning is sounded as the bore reaches Blackstone Point at New Barns Bay, around 5 minutes before the bore reaches Arnside pier. It has to be said that giving timings for the bore is not an exact science in the way that tidetables are.

The estuary has an HM Coastguard rescue team based at Arnside, who operate a rescue craft in the Bay, with additional rescue services provide by the RLNI at Morecambe and the Bay Search and Rescue group at Flookburgh.




Arnside Bore filmed on 1st August 2011 by Tony Riden, AONB Countryside Officer