Understanding Tide Times for Safe Coastal Foraging

Why the tide decides your day

Foraging on the shore is a wonderful way to spend a morning, but the sea is not a fixed landscape. It is a moving one. A rockpool you stepped across at ten in the morning can be a chest-deep channel by four in the afternoon, and a sandbank that looked like solid ground can be split by a gully you never noticed on the way out. Most coastal incidents involving people who simply meant to pick a few mussels begin with the same sentence: “I didn’t realise it came in that fast.”

The good news is that tides are one of the few things in the outdoors that you can predict with remarkable accuracy. Learn to read a tide table properly and you gain both safety and access — the lowest shores, the richest pools, and the seaweed beds that are only exposed for a couple of hours each month.

Reading a tide table without a degree in it

A tide table gives you two things for any given day: the time of high and low water, and the height of the water in metres, measured from a local fixed baseline called chart datum. Those heights matter more than the times. A “low water” of 0.4 metres leaves a very different shore from one of 2.1 metres.

• Find your local table. Harbour offices, chandleries, some newsagents and tourist information points still produce printed tables. A photograph on your phone is fine, but a folded paper copy in your pocket works when the screen dies.
• Check the time zone. British tables switch between GMT and BST. An hour’s error can be the difference between walking out and swimming back.
• Note the range. Subtract low water from high water to see how much water is moving. A range of five metres means a fast, powerful tide on a shallow beach.
• Work backwards. Pick your low-water time, then plan to be off the foreshore at least ninety minutes to two hours before the next high water, depending on the range.

Springs, neaps, and the shape of your window

Tides run in a fortnightly rhythm. Around the new moon and the full moon you get spring tides: the biggest ranges, the lowest low waters and the fastest-moving water in between. These are the days for reaching the outer reefs and the kelp beds that are normally underwater — but they are also the days when the sea comes back quickest, so your return window is tighter than the numbers suggest.

Around the quarter moons come neap tides, with smaller ranges and gentler movement. Neaps are kind to beginners and to anyone exploring a narrow estuary, but the lowest of the shore may simply never appear. Onshore winds and low pressure can push water higher than the table predicts, sometimes by a considerable margin; a strong westerly against a spring high water is not the day for an exposed headland.

Footwork and kit for a slippery shore

Wet seaweed on rock is the single most underrated hazard on the coast. Falls happen quietly and often on the walk back, when legs are tired and the bag is heavy. Your footwear is your first piece of safety equipment.

• Grippy boots with deep tread, or studded soles. Smooth-soled wellingtons are fine for sand and shingle, dangerous on wet rock and clay.
• A walking pole or staff for balance on sloping rock shelves and in gullies.
• A watch, a whistle and a small torch — even on a July afternoon.
• A dry bag or waterproof pouch for your phone, plus a spare warm layer. Sea air is cold once you stop moving.
• A tide table on paper and a note of your planned return time left with someone at home.
• Gloves for handling barnacled rock and limpets.

Never wade through water to reach a promising pool. If you cannot see the bottom, you cannot see the drop, the current or the soft mud.

The turn of the tide and getting back with time in hand

Low water is not a pause. The sea tends to hang for ten or twenty minutes and then begin to fill, and on a flat beach the first stretch of the flood can creep around behind you without any obvious sound or surge. This is the moment to be off the ground you crossed on the way out.

Before you start filling a bag, turn around and study the route back. Pick out landmarks — a distinctive boulder, a cliff notch, a line of gorse — because a shore looks entirely different with the light behind you. Check whether a headland or a spit could cut off your return, and know where the nearest high ground or path is. Rip currents in gullies and channels are real; if you are caught in one, do not fight it — float, go with it, and angle sideways towards the shore.

Keep glancing at the water, not just at the rocks. If the weed you are standing on starts to lift and float, the tide is already there.

Foraging with care, and knowing when to walk away

Take greens and seaweeds rather than shellfish if you are new to this. Sea beet, orache and samphire should be cut with scissors, leaving the roots and holdfasts intact so the plant regrows. Never strip a rock bare; take a little from many places.

Bivalves such as mussels, cockles and oysters filter the water they live in, which means they concentrate whatever is in it. Always check local notices for harvesting closures before you collect them, avoid estuaries near outfalls or marinas, and cook shellfish thoroughly. If a notice is up, or the water looks discoloured, or you simply are not sure — leave it. The shore will still be there next spring, and so will the next low tide.