There are 43 tidal islands around the UK, accessible just briefly each day, along beguiling and perilous paths.
As the tide retreats, five writers walk their favourite causeway to islands of refuge, pilgrimage, magic and glamour.
Today, Evie Wyld boards the ferry at Lymington pier and retraces a path well-travelled with her family during school holidays - across the Freshwater Causeway on the Isle of Wight. Her route takes her past ghost benches, a graveyard, World War Two pill boxes on a journey through grief, memory and what survives the tide.
Across the series:
Claire McGowan sees time change as she enters the freezing waters off Burgh Island and sips cocktails in the art deco hotel bar.
Ben Cottam almost gets stuck in the mud as he searches for the grave of a black slave and questions his family’s past at Sunderland Point.
WN Herbert follows in the footsteps of pilgrims to Lindisfarne and reflects on the causeway leading to a meditational space.
And between kite surfers and dog walkers, Patrick Gale is suspended between two worlds as he follows the S shaped causeway, shaped by relentless tides and currents to St Michael’s Mount.
As sea levels rise and the sands shift, causeways are in flux. The essayists draw us down onto the sands, revealing what these liminal routes mean to both them and the cultural history of the UK.
Producer: Mohini Patel