Bory Tucholskie

When the last ice sheet paused over Pomerania, its meltwater rivers spread apron after apron of sand — and on that outwash grew the Bory Tucholskie, one of the largest continuous pine forests in Poland. The national park, declared in 1996, protects the choicest piece of it: the Struga Siedmiu Jezior, a modest stream that threads seven kettle lakes strung through the pines like beads, from Ostrowite down toward Charzykowskie. Since 2010 the park has been the core of a UNESCO biosphere reserve covering the whole forest region.

The lakes are the treasure, and the rarest of them are the lobelia lakes — Wielkie Gacno and its siblings — so starved of nutrients that the water sits glass-clear over pale sand, colonised by water lobelia and quillwort, plants of an almost Scandinavian austerity that vanish at the first whiff of fertiliser. Ostrowite, the biggest lake, holds that same clarity at swimming-pool scale: from the footbridges you watch pike hanging mid-water as if suspended in air. On land the show is quieter — carpets of reindeer lichen crunching underfoot in the dry pine heath, sundews on the bog margins, cranes bugling from the mosses, white-tailed eagles working the lake chain, and on June nights the churring of nightjars along the sandy fire-roads.

People have always worked these unpromising sands rather than farmed them. The Borowiacy — the forest's own ethnographic group, between Kashubia and Kociewie — burnt tar, kept forest bees in hollowed pines, and floated timber down the Brda; their successors invented Polish freshwater sailing at Charzykowy, where the country's first inland yacht club opened in 1922 on Charzykowskie's long water.

What's worth knowing before you go

Charzykowy, just outside the park on Lake Charzykowskie, is the natural base, with the rail-junction town of Chojnice a few kilometres away providing connections toward Gdańsk and Poznań. The park itself is walked and cycled on flat, well-marked sand tracks — the loop linking the Struga's seven lakes is the essential day — and swimming is sensibly channelled to designated spots, since a season of sunscreen would be enough to cloud a lobelia lake for good.

June gives nightjars and the longest light; late September gives amber pines, empty trails and mushroom smells, though picking inside the park boundary stays forbidden. Winter is silent and grey-gold and has its devotees. The connoisseur's moment is dusk on a warm June evening on the sand road south of Ostrowite: nightjars churring invisibly on both sides, and the resin smell of a day's heat lifting off the pines.