A tarn sits high, in a hollow, usually reached by a path that climbs steeply and then turns to loose scree, wet grass and peat. Then you swim, and then you walk down on cold, wet feet. That combination is far more demanding than a dry summer ramble along a valley track.
What you need is a boot that holds your foot still on the descent, resists water long enough to get you back to the car, and grips rock that is slick with rain or algae. Get the fit right and everything else — warmth, balance, blister-free miles — tends to follow.
Before you care about anything else, your heel must sit deep in the heel cup and stay there. If your heel lifts even a centimetre when you stride uphill, you will get rubbing, and on a long descent you will jam your toes into the front of the boot. That is how black toenails happen.
Test it in the shop:
A good lacing trick: keep the lower section moderately snug, then use a heel lock. Cross the laces, feed each end back through the loop on the same side, then tie. This pulls the heel back into the cup. Many boots have a second locking hook near the ankle designed for exactly this.
Aim for roughly a thumb's width between your longest toe and the front of the boot while standing with weight on both feet. That gap matters most downhill, when your foot slides forward. Feet also swell over a long day and after a cold plunge, so a snug-but-not-tight fit in the shop will feel tight by teatime.
Try boots on with the socks you actually wear — usually a mid-weight merino pair, thinner in summer. If you plan to swim, remember you may end up walking in the boots with damp or wet feet. Wet skin loses its grip on the lining, so the heel lock matters even more.
On width: many British fell walkers have broad forefeet and narrow heels. Look for a wider toe box with genuinely good heel hold. Narrower feet often suit a women's-specific last better. Never buy for length alone.
Tarn country means wet rock: the greasy slab beside the outflow, the algae-covered stones at a stream crossing, the polished slate of an old quarry track. You want soft, sticky rubber and deep, well-spaced lugs.
Boots wear out from the midsole up. If the sole still looks fine but the boot twists easily in your hands, it is finished.
For most upland tarns you do not need a wading boot. You need a boot that can get wet and still be walked in. Leather uppers soak and become heavy; synthetic and mixed uppers dry faster. Waterproof-breathable linings keep splashes out but trap water in once it comes over the top, so a swim in a tarn means wet feet regardless.
A practical routine: carry a light pair of trainers or river sandals in the rucksack for the swim and the walk back, or simply accept wet boots and wear wool socks, which stay warm when damp. Never swim in your boots.
Dry them away from direct heat. A radiator will crack leather and shrink the lining, and a boot that no longer fits is worse than a boot that is wet.
Before you commit to a long tarn day, do three short walks: one on tarmac and gravel, one up a steep grassy slope, and one in the rain. Then a two-hour walk with a loaded rucksack. Heel lift and hot spots show up within an hour, not ten miles in.
Keep the receipt and the box, and return them unworn if you can. If a boot creases painfully across the top of your foot, no insole or lacing tweak will cure it — choose again. The right pair should feel secure from the first step, not after a month of suffering.
Get a boot that locks your heel, frees your toes and bites into wet rock, and the high tarns of the Lakes, Snowdonia and the Highlands open up as they should: a swim at the top of a long climb, and a descent you actually enjoy.
Northern Tarn shares practical, down-to-earth guidance on upland tarns, fell walking and wild swimming in northern britain for readers across the UK.
Leave A Comment