The programme takes us on a trip across the north Wales coast from Aberystwyth up to the Dee.

For centuries there's been a tale of a Welsh Atlantis lost beneath the waves. The story is that the bay of Borth Sands was once fertile land, but was lost to the sea. Historian Neil Oliver meets folklore expert Twm Elias who tells him all about The Sunken Forest of Borth.

The entire coastal waters of Cardigan Bay are a haven for wildlife and a perfect breeding ground for seabirds. There is a wealth of marine mammals, but there is one creature which goes to extraordinary lengths to reach this stretch of coast. Zoologist Miranda Krestovnikoff goes in search of the giant leatherback turtles that for centuries have been making the long journey from Bermuda to the bay beyond Porthmadog.

Portmeirion is also en route along the west coast of Wales. Geographer Nicholas Crane turns 'prisoner' and relives moments from the 1960s television series.

Crane canoes in some of the most treacherous waters in the UK - the Menai Strait - to tell the story of two great bridges and the engineers who built them. In the 1830s the dash was on to get from London to Dublin, which resulted in Thomas Telford's designs for the Menai Bridge and Robert Stephenson's 'Box Girder' bridge invention which was copied around the world.

Dr Alice Roberts delves into the underground caves of the Great Orme, a Bronze Age civilisation which sits side by side with the holiday resort of Llandudno.