Why the Tide Matters Here
A beach that is wide and welcoming at one time of day can be nearly gone a few hours later. The Cornish coast has a considerable tidal range in many places, and sandy coves, rocky platforms and caves can all be affected. This article focuses on the practical skill of reading the information available to you.
Looking at a tide table takes a couple of minutes and is one of the most useful safety habits for any beach day. It can tell you when the sand is largest, when rock pools are accessible, and, most importantly, when a route back might be cut off.
What a Tide Table Shows
A tide table lists the times of high water and low water for a particular place on a particular day, along with a height for each. Most coastlines in the UK have two highs and two lows in roughly a 24-hour period, with the cycle moving later each day. As a rough guide, there are a little over six hours between high and low, but the exact intervals vary, so use the printed times rather than doing the arithmetic yourself.
A typical entry has these pieces:
- Date and place. Tables are specific to a location, usually a main port. Check whether the entry is for your beach or a nearby harbor, since times can differ between places even a short distance apart.
- Times. Each high and low has a time, and it is worth checking whether the time is given in local time, which includes daylight saving in summer, or in another standard. If the table does not say, look for a note.
- Heights. These are given in meters above a reference level called chart datum, which is roughly the lowest level the tide is expected to reach. A high of, say, 5.5 meters and a low of 0.5 meters means a range of 5 meters.
- Notes. Some tables include moon phases, sunrise and sunset times, or a marker for spring and neap tides.
Providers present this differently, in printed booklets, harbor notices, websites and apps, but the information is similar. Where you can, check one source against another.
Spring Tides and Neap Tides
The size of the tide changes over about a two-week cycle. Around new moon and full moon, the range is larger: high tides go higher, and low tides go lower. These are called spring tides, which has nothing to do with the season. About a week later, around the moon’s quarters, the range is smaller, and these are called neap tides.
This matters for planning. On spring tides, a beach can have far more sand at low water, which is attractive for walking, but the water also comes in higher and can move quickly across flat sand. On neap tides, the change is more modest. Weather can also push the tide higher or lower than the table predicts. Strong onshore winds and low air pressure can raise sea levels, and big swells can wash well above the predicted line, so the table is a guide rather than a guarantee.
What “Cut Off” Means
Many Cornish beaches are backed by cliffs, and some coves are linked to one another only across sand or rock at low water. A cut-off beach is one where the incoming tide covers the route out, or the only access, leaving people stranded at the base of a cliff. This is a recognized cause of rescues around the coast.
The situation can develop quietly. Flat beaches fill from the sides and behind, so water can reach the path you walked in on before it reaches your towel. Rocky headlands can be passable at low water and impassable an hour or two later. You may not notice until the way back is already under water.
Some points to keep in mind:
- Look at the tide table and note the time of high water before you go onto a beach, not after.
- Aim to be back at your exit point well before the tide has come in, giving yourself a generous margin.
- Be especially careful when the tide is rising, as it can come in faster than you expect on gently sloping sand.
- Do not rely on climbing cliffs to escape, as they are often unstable and can be much harder to climb than they look.
- If you are unsure how to leave a beach safely, check for local signs or ask a lifeguard before you go.
A Simple Routine
- Check the high and low water times for your location and the day you are visiting.
- Work out when the tide will be low enough to reach what you want, whether that is rock pools, a cave or a stretch of sand, and when it will turn.
- Decide your latest safe time to leave and set an alarm on your phone.
- Check the weather forecast and sea conditions, as swell and wind can change how a beach behaves.
- Look for signs, flags and notices on arrival, and follow them. Lifeguard-patrolled areas have flags that explain conditions, and the ones for rip currents are worth learning before you go in the water.
Using the Tide to Your Advantage
Understanding the tide also improves a beach day. Low water is a good time to explore rock pools and see the seashore life, which can be fascinating, though you should leave animals where they are and watch your footing on wet, weedy rock. High water at some beaches leaves only a narrow strip of dry sand, so arriving then can mean crowding and less room to spread out.
When in Doubt
Tide tables are a tool, not a promise. If a plan depends on squeezing through a narrow window, it is usually better to choose a different beach. Cornwall has plenty of them, and a day that ends with everyone safe and dry is a good day.