Learn the Beach Before You Swim It

Every bay has a personality that changes with the tide, the wind and the season. Before you pull on a wetsuit, spend five minutes reading it. Check the tide times: a beach that gives you a gentle paddle at high water can leave you a quarter of a mile from the sea two hours later, with soft sand or sticky mud between you and dry land. Look at the wind — an onshore breeze over an exposed bay builds chop quickly — and check the swell forecast if you plan to go deeper than your waist.

Watch the water before you enter it. Those flat, darker patches between waves often mark a rip, and the churn around rocks, groynes and harbour walls tells you where the current runs. Where lifeguards patrol, swim between the red and yellow flags. A single red flag means the water is closed, and a black and white chequered flag marks a zone for surfboards and kayaks rather than swimmers. Walk in slowly, let the cold settle, and keep your first swim of the day short.

Give Anglers and Their Lines a Wide Berth

Anglers and swimmers share the same coastline, often at the same hours, and they coexist perfectly well with a little distance between them. A sea angler casting from a beach, rock ledge or breakwater can send a baited line a hundred metres or more, and hooks travel with it. The line itself is thin, often grey or clear, and close to invisible in low light or choppy water.

Keep a generous margin — at least fifty metres from any rod — and never swim into the casting arc, which generally points out to sea from the angler's shoulder. Walk along the beach rather than between a rod and the water. At dusk and through the night, look for headtorches, small lights on rod tips, and the silhouette of a tripod against the sky.

• Never swim over or through a line, even if it looks slack; hooks and weights sink well below the surface.
• If you snag or tangle a line, tell the angler instead of pulling it free — lost line becomes a hazard for birds, seals and other swimmers.
• Keep dogs and children well back from buckets, bait and tackle bags, which often hold sharp hooks.
• If you spot discarded line or hooks on sand or rocks, pick them up if it is safe and put them in a bin.

Stay Clear of Boat Lanes and Launching Slipways

Harbours, estuary mouths and popular bays are working waterways. Ferries, fishing boats, dive boats, RIBs, kayakers and paddleboarders all use the same water, and the channels they follow are usually marked by buoys, posts or leading lights. Treat the line between two markers as you would a road.

Cross channels at a right angle, in a group if you can, and keep moving. Stay well clear of harbour walls, mooring chains, pontoons and slipways. A boat being launched from a slipway has limited visibility and almost no ability to stop quickly, and the same goes for a kayak or paddleboard being carried to the water by hand.

Listen as well as look. A propeller in gear makes a low, churning sound that carries across water, and an engine you can hear behind you deserves a glance over your shoulder. In busy summer bays, swim parallel to the shore rather than striking out for open water, and stay inside the area you have already read.

Be Visible and Predictable Around Other Water Users

On a shared beach, being seen is both a courtesy and a safety measure. A bright swim hat, a tow float and a dry bag you can clip on make a real difference — not only to boats, but to kayakers, paddleboarders, surfers and other swimmers. In low sun, a dark head in dark water is almost impossible to spot from twenty metres away.

Be predictable. Swim steady lines, avoid sudden changes of direction in front of other people, and don't stop dead in a busy channel. If you are part of a group, agree a route and a meeting point before you get in, and have one person keep an eye on the shore. Never swim alone in unfamiliar water.

Give other people space at the water's edge, too. Surfers need the breaking waves, paddleboarders and kitesurfers need a clear launch and run, and dog walkers and horse riders use the open sand at low tide. A friendly wave and a wide berth solve almost every conflict on the foreshore.

Leave the Sand and Rocks as You Found Them

Everything you take onto the beach needs to come home with you. Sea swimming kit is light, so a small mesh bag tucked into a tow float or rucksack makes it easy: wrappers, plasters, hair ties, drinks cans and the inevitable single lost sock. Cigarette butts are plastic and take years to break down, and so-called biodegradable wipes and fruit peel belong in the bin rather than on the sand.

Fishing line, hooks, balloon ribbon and nurdles — the tiny plastic pellets that wash up in drifts — are always worth picking up, because wildlife mistakes them for food and swimmers find them the hard way. Leave seaweed, limpets and rock pools as they are; they are somebody's home. Don't build cairns or shift boulders on the foreshore, and keep off the sand dunes, which are fragile and slow to recover.

Leave the shore as you found it, and the next swimmer — and the next generation of them — gets to enjoy the same bay.