The Places the Road Cannot Reach

Some of the best sand in Britain lies at the bottom of a cliff, at the end of a path that was never meant for a car. No car park, no ice cream van, no litter bin. Just a strip of sand, a stack of rock, and whoever else has decided to spend an afternoon earning their swim. These coves ask for something in return: a look at the tide table, a proper packed lunch, boots with actual tread, and a willingness to turn back if the sea says no.

What follows is a guide to the kind of beaches you find by accident and then guard a little jealously. They exist all around the coast, but the south-west peninsula and the Scottish north-west are where the habit really takes hold.

Reading the Tide Before You Read the Map

The first thing to understand is that the tide does not rise like water in a bath. It comes around headlands and fills in behind you. A cove you walked into over dry sand at eleven o'clock can have its exit underwater by two, and the return route up the cliff is often the only one there is. On a spring tide the water can move faster than you walk over rough ground, so the old rule of twelfths is worth keeping in your head: in the first hour after low water the sea rises roughly one twelfth of its range, then two twelfths, then three, then three, then two, then one. The middle hours are the ones that catch people out.

• Neap tides give you a longer window but may leave rocks and weed exposed where you hoped for sand.
• Spring tides open up the widest beaches and close the exits quickest. Treat the two hours either side of low water as yours.
• Wind matters as much as the tide. A stiff onshore blow can push water and swell into places the tide table never mentions.

Coves of the South-West

Cornwall is the classic hunting ground. Nanjizal, a mile or so of clifftop walking east of Land's End, rewards the descent with a narrow, boulder-flanked beach and a rock arch that frames the sea like a window. Nearby Porthchapel and the coves below the Zennor cliffs are smaller, quieter and steeper still. Further along the south coast, Lantic Bay near Fowey is the template for this whole genre: a beautiful pale beach with a punishing pull back up to the clifftop, and an exit that vanishes under high water.

Devon and Dorset have their own versions. Soar Mill Cove, tucked between Bolt Head and Bolt Tail, is reached by a valley path that is gentle on the way down and noticeably less so on the way back. Over in Purbeck, Chapman's Pool sits in a fold of cliff below the South West Coast Path, popular enough for a small car park at the top and still wild enough that a school of mackerel or a seal will turn up unannounced. Take a torch if you are heading back over the last ridge in the evening; the chalk gets slippery and the light goes early under the cliffs.

Scotland's Atlantic Edge

North of the border the scale changes. Sandwood Bay, in the far north-west of Sutherland, requires a walk of around four miles each way across moorland from the end of the single-track road, and pays you back with a mile of pink sand, a sea stack and a reputation for sudden weather. There is no shelter, no phone signal worth relying on, and midges in season that will treat your lunch as theirs. Carry everything out; there are no bins and no facilities.

The Mull of Galloway, the sandy coves of Wester Ross and the shingle inlets along the Fife coast offer gentler versions of the same bargain. On the Atlantic side especially, the water is cold enough to take your breath away in August, and a dip of two minutes is a respectable outing. If you want a niche pastime to go with it, sea swimming in these coves at low water, followed by a flask of tea on the clifftop, is about as good as a British afternoon gets.

What Goes in the Pack

• Water — a litre and a half each for a half-day walk. There is nowhere to refill.
• Footwear with grip, not fashion. Wet granite and loose shale do not negotiate.
• A paper map of the right scale, and the knowledge to read it. Phone batteries die in the cold and the damp.
• Layers and a windproof. Coastal headlands can be five degrees cooler than the car.
• Cash for an honesty box or a village shop on the way home.
• A bag for your rubbish, and a spare for someone else's.

The Unwritten Rules of a Secret Beach

These places stay lovely because people treat them carefully. Between March and July, keep to the path and keep dogs close, because cliff ledges are nesting grounds for fulmars, guillemots and peregrines, and a flushed bird may abandon its eggs. Light no fires on the sand or the heath. Remove shellfish only for your own tea, and check local rules before you take anything at all.

And resist the urge to broadcast every detail. Half the pleasure is in the finding, and half the reason these coves remain quiet is that not everyone can be bothered with the walk. Tell a friend, by all means, but tell them about the tide, the steep bit at the end, and the fact that the reward is worth the climb back up.