Imagine you’re walking along a beach, talking to your friend, enjoying the sunshine. Time goes by and it’s time to head back. But as you approach the headland you had walked around previously, you realise that’s not possible anymore: the tide has come in and there is no path around it now. You’re trapped in a bay with the tide continuing to submerge the beach.

The scary, and sometimes life-threatening, experience of being cut off by the tide is not as rare as you might think. Our survey found that millions of people – 15% of the UK public – have been cut off by the tide (or nearly so) at least once.

Often there is a simple enough solution, such as climbing up a hill or getting your feet wet. But sometimes there is no easy way out, and the danger increases quickly as the water level rises fast.

That’s when it is essential to call for help. Since 2020, tidal cut-offs in the British Isles have resulted in around 3,600 Royal National Lifeboat Institution (RNLI) lifeboat and lifeguard rescues, with some 35,500 people being assisted.

This high frequency of tidal cut-offs tells us that getting into danger is not down to exceptional misfortune or, as some might think, people’s own stupidity. It is much too common for that. Our survey shows there are systematic reasons – in particular, misconceptions about how the tide works – that regularly lead to people getting into difficulty.

The tide is principally driven by the gravitational pull of the Moon and Sun. But because their positions relative to the Earth are always changing, and the coastal geography varies, tidal movements are more complex than most people realise.

The gravitational pull of the Moon is strongest during full and new Moons. This leads to larger tides every two weeks, known as spring tides. The Sun has a stronger effect when it is closest to the equator, so tidal changes near the spring and autumn equinoxes are greater.

The timing and height of tides therefore vary widely in both time and space. When school holidays coincide with large spring tides, the risk of incidents increases.

Tidal literacy

To avoid getting cut off by the tide, be aware of what the water is doing – even if you don’t intend to go swimming. In our study, 60% of those cut off were never intending to enter the water. They were simply engaging in activities on the shore such as walking, rockpooling, dog walking and fishing.

Four in ten people in our survey were unaware that tides come in twice daily, that they vary in timing each day, and that they differ in height across the country. So, even if you’ve seen and understood the effects of tidal movement in one place, you won’t automatically know how it works elsewhere and at a different time.

Despite this variation, tides can be predicted accurately and tide tables are publicly available online which show tidal movements in different locations. Every time you visit the coast, choose a website you trust and understand, and work out what the tide will be doing when.

This useful habit requires some practice. Over a quarter of our survey respondents struggled with basic tide-table reading, and only a quarter could extract more complex information – such as when to safely return from a walk to an island that is cut off from land at high tide.

Many people overestimate their ability. So, don’t just rely on your own knowledge – if you’re visiting a place for the first time, ask the locals, coastguards or RNLI about any specific dangers.

In some places such as sand or mudflats, the tide can come in faster than you can run – especially if it comes in behind you, cutting you off from the safe shore. The word “flat” is very misleading, as these areas are usually scattered with deceptive channels and creeks.

Our survey revealed that many people believe the tide comes in slowly, consistently and directly toward the shore, and this is what can easily result in dangerous situations. In reality, the water uses the uneven surface to advance from various directions, and can unexpectedly and very rapidly cut off sandbanks from behind.

As you walk around headlands, cross a causeway or head out on to sand flats, always make sure there is an escape route should the tide behave in unexpected ways. Stay alert: being distracted frequently leads to being cut off, according to our survey participants.

Efforts are underway to restore society’s relationship with the sea, including via the worldwide ocean literacy agenda. Wales is the first country to include “safe access” in its national ocean literacy strategy. Hopefully, other countries will follow suit.

By highlighting the extent of misconceptions around tides for the first time, the insights from our survey suggest that ocean literacy should include understanding of tides. This will enable safe and enjoyable access to coasts, nurturing positive relationships and behaviour that support the planet’s health.