In Northumberland, Tori and Alex investigate the tragic story of a French fishing trawler that was wrecked in 1913, and discover the ancient community that thrived in the Middle Ages in what is now one of the north-east's top tourist destinations.

Every day, on a sandy beach or a rocky foreshore, fascinating evidence of Britain's island history appears and disappears as the tide rolls in and rolls back out again. Tori Herridge and Alex Langlands reveal stories from our extraordinary maritime, industrial and natural history. In this episode, Tori and Alex explore Lancashire's coastal archaeology. They investigate a beach full of building rubble from World War II, track down Liverpool's own version of the Whisky Galore story, and find evidence of people and animals dating back 7000 years.

Every day, on a sandy beach or a rocky foreshore, fascinating evidence of Britain's island history appears and disappears as the tide rolls in and rolls back out again. Tori Herridge and Alex Langlands reveal stories from our extraordinary maritime, industrial and natural history. In Essex, Tori and Alex investigate the earthwork remains of a fort dating to the time when Henry VIII took England out of the European Catholic union. They pay their respects to some Thames sailing barges that are now sunk in estuary mud but which were once the glory of the east coast. And they find a First World War German U-boat stranded in a tiny creek.

In East Sussex Tori explores the wreck of a ship that went down in the 1740s complete with its cargo, and uncorks a bottle found on board, still full of 18th-century red wine. She discovers a prehistoric well shaft that is now on the foreshore but 2000 years ago would have been inland. And she investigates the story behind a harbour that was intended to serve the village of Rye. It took 63 years to build and then closed down after only four months.

In Dorset, Tori and the team reveal the story of the world's first aircraft carriers. They also discover how this coastline played a vital role in D-Day and search for a unique and huge Iron Age monument that can only be seen - sometimes - for a few hours a year.

Tori examines various attempts to make the River Clyde deeper to get ships into the heart of Glasgow, and investigates the role of an odd-shaped vessel in a boat graveyard

In this episode Tori visits the Severn Estuary and investigates a mysterious medieval ruin on a bleak island. Who built it, and why? Could it have been a religious site? Was it an early lighthouse or beacon? Further along the coast she visits the site of the medieval village of Sudbrook, which simply disappeared into the sea. She finds out how important the ferry crossing at Aust was during the 20th century and is shown a photo of a famous passenger who used it: Bob Dylan. And she investigates the story behind the very first attempt to build a tunnel underneath the Severn. At the moment, all this archaeology is available to anyone who cares to go looking for it, but rising sea levels and coastal erosion mean it won't be very long before it's all swept away. Britain at Low Tide captures a vanishing past for us all to see.

In East Yorkshire, Tori uncovers the story behind a dramatic night when a fishing trawler went wildly off course in the North Sea. The massive remains of a World War I fort lead Tori to tales of love in a Yorkshire village. And she learns the strange fate of two ships that were built in Hull but ended up on top of a mountain in Peru.

In Fife, Tori explores a wreck near the scene of one of Britain's worst ever railway disasters and examines stone carvings left in caves by one of Scotland's oldest tribes.