On the highest tides, a most unusual sight can be seen in the Kent Estuary in Morecambe Bay called the Arnside Bore. This is one of about twenty tidal bores that occurs in the UK and is named after the village of Arnside. It is quite a spectacle and often draws crowds of onlookers.
The source of the Kent is the Kentmere Valley near Ambleside and the river then flows down through Kendal to Morecambe Bay. Arnside is on the southeastern side of the estuary and is a pleasant place to wander with a good choice of shops, pubs and cafes. Along with scenic views of the distant Lake District fells, there is a much-photographed railway viaduct that carries the coastal railway. The tree-covered slopes of nearby Arnside Knott are a good place for views of the estuary, including a plaque showing the names of hills in the distance.
One feature of the estuary is its high tidal range and many people have been caught out by the tides over the years. Signs on the promenade warn about the dangers of fast rising tides, quicksand and hidden channels. Due to the risks, during daylight hours in the tourist season the council sounds a warning siren twice as the tide advances.
When conditions are right, the siren also serves as an indication that the Arnside Bore is approaching. The first blast typically occurs about 15-20 minutes before the wave arrives and the second as it passes New Barns Bay near Blackstone Point.
The speed and power of the wave can be most impressive to see. Usually it dissipates on reaching the viaduct but sometimes it travels further inland to Sandside and the mouth of the River Bela. However, it is smaller and less predictable here. There have also been occasional sightings from the opposite shores near Grange-over-Sands.
As with any natural phenomenon, sightings are not guaranteed and only occur under certain conditions, so search online if interested to find out when best to visit. Often this is in spring or autumn although online videos can be found from most months of the year. The website of the Arnside and Silverdale AONB provides a useful starting point for more information. Factors that can affect the wave’s passage include onshore winds, low pressure in the Irish Sea and high flows in the River Kent.
The most popular viewpoint is the promenade in Arnside. Water levels rise quickly once the wave passes so it is important to keep off the sands and mudflats. The car park near the railway viaduct is prone to flooding and in extreme tides part of the road between Arnside and Milnthorpe floods too. The RNLI website has some excellent advice on water safety.
If you would like to learn more about tidal bores, follow these links for posts on why tidal bores form and the spring and autumn equinoxes. This post also describes the Mersey Tidal Bore which begins near Liverpool and ends in Warrington. It is shown briefly in this video about a book I published on places to visit around the Mersey Estuary and its history and wildlife.
Two new books describing tidal bores
If you are interested to learn more about tidal bores, I have two books due out soon with more information. The first The Cumbria and Lake District Coast includes viewing tips for several around Morecambe Bay, Cumbria and the Solway Firth, along with ideas for places to visit and the history and wildlife of these areas. You can read more about it on this webpage. The second is an ebook specifically on the tidal bores of the UK – of which there are more than twenty – and I’ll be posting details about that on this website soon.
Note: this post is an updated version of an article first published in February 2020