Reading the shoreline before you pick anything up

The best beachcombing happens on a falling tide, ideally a spring tide when the sea has reached further up the beach than usual. Aim to arrive about two hours before low water and work the strandline – the dark ribbon of weed, shells and debris left by the last high tide – as it is exposed. Stormy weather from the west or north is your friend: it churns up deeper material and throws fresh finds onto the shore. Winter and early spring give the richest hauls on most UK coasts, while late summer often brings a flush of shells after the breeding season.

Walk parallel to the water, scanning just ahead of your feet, then loop back along a slightly higher line. Gravel patches, the lee side of groynes and the top edge of shingle banks all trap small, heavy items. Always check a tide table before you set out, and never let the sea get behind you on a flat, fast-filling beach.

Sea glass: how to tell a true find from a fresh break

Genuine sea glass has been tumbled for decades, sometimes a century or more, and it shows. Look for a soft, frosted surface, rounded and slightly irregular edges, and a shape worn into a pebble rather than a shard. Hold it up to the light – you should see a gentle glow with fine internal bubbles or faint crescent marks where the glass was originally moulded. If the edges are sharp, or one face is flat and shiny, it has not finished its journey; leave it where it is or pop it back into the surf line.

Colour is the great thrill of sea glass hunting. The everyday finds are bottle green, white and brown. Rarer and more rewarding are:

• Pale blue – often from old medicine or Milk of Magnesia bottles.
• Cobalt blue – ink, poison and some cosmetic bottles.
• Amber and dark olive – beer and spirit bottles, sometimes Victorian.
• Red, orange and pink – the true prizes, usually from maritime lamps, tail lights or old tableware.
• Purple – clear glass that has been exposed to sunlight for years and slowly changed colour.

Wear gloves or use a scoop, because glass in the shallows can still cut, and rinse your finds in fresh water before storing them.

Common shells and other strandline treasures

Around the UK you can expect to meet a familiar cast. Blue-black mussel shells, ribbed cockles, rough limpets and the pointed spiral of a dog whelk turn up almost everywhere. Scrunch your toes into the sand at low water and you may find razor shells, and after a gale the big fan-shaped scallops and thick oyster shells arrive from offshore beds. Cuttlefish bone, bleached white and chalky, is a regular find, as are the dark, papery egg cases of rays and skates – once called mermaid's purses. Whelk egg cases, looking like clusters of small leathery purses, are another giveaway.

Two rules of thumb will keep you on the right side of the wildlife. First, if there is an animal inside, put it back gently in the shallows – a sealed winkles or limpet clamped to a rock is very much alive. Second, crab shells that are hollow, crisp and perfect are usually moults, not bodies, so they are fine to admire and return.

Recording your discoveries

A small notebook turns a pleasant walk into real natural history. Note the date, beach name, state of the tide, weather over the previous days, and where the find sat in relation to the strandline. Photograph each interesting piece against a coin or a ruler for scale, and take both the top and the underside – many shells are identified by the hinge or the aperture. A rough grid reference from an Ordnance Survey map, or a simple description such as "twenty metres east of the slipway", makes your record useful to others.

Keep a seasonal log and patterns will emerge: a run of slipper limpets in one bay, a sudden abundance of sea urchin tests after a storm, a stretch of coast where sea glass is unusually common. If you find something you cannot identify, a local museum, wildlife trust or marine recording scheme will usually be delighted to help.

Staying safe on the strandline

Beachcombing is low-risk but not risk-free. Sturdy shoes with grip are essential on wet rock and weed, and a pair of gardening gloves or neoprene gloves will save your fingers from glass, rusty metal and the occasional needle. Carry a small first-aid kit and hand gel, and wash your hands before eating. Watch for weever fish in shallow sand, jellyfish in summer and autumn, and seals or seal pups hauled out on remote shores – keep well back and keep dogs away.

Mobile signal is patchy on many beaches, so tell someone your route and expected return time. Cold water shock is a real danger even in summer, so resist the urge to wade out to a tempting find.

Following local rules and protecting fragile habitats

Many of our finest shorelines sit within Sites of Special Scientific Interest, Marine Conservation Zones or nature reserves, and some have byelaws restricting what may be taken. Check signage at the car park and any local notices before you start. As a general principle, take only a few small pieces for personal interest, never strip a beach, and leave the strandline largely intact – it feeds turnstones, twites and other hungry winter visitors.

• Never prise living creatures from rocks, and do not turn boulders on shores where this disturbs sensitive communities.
• Do not collect seaweed still attached to rock, or any plant or animal that is alive.
• Keep dogs on leads where ground-nesting birds such as ringed plover and oystercatcher breed.
• Report unusual finds rather than removing them, especially if they may be of scientific interest.
• Take litter home, including any fishing line you find – it is lethal to birds and seals.

Comb the shore with curiosity, tread lightly, and the coast will keep rewarding you for years.