In 1826 messages went from Holyhead to Liverpool in seconds without pigeons or Morse code. (R)
BBC Two except East, Scotland, Yorkshire
The team visit the limestone headland of the Great Orme in Llandudno, north Wales.
BBC Two Wales
Alice Roberts goes prospecting for oil along the Jurassic coastline.
8/13 Nicholas Crane travels from Cape Wrath to Wick near John O'Groats. (R)
BBC Two except East, Wales, Yorkshire
From Dublin to Belfast, a look at how the sea has shaped the island of Ireland. (R)
Nicholas Crane discovers fossils and the early course of the Thames. (R)
BBC Two except East, Yorkshire
Historian Neil Oliver investigates the Victorian Channel Tunnel. (R)
BBC Two England
Zoologist Miranda Krestovnikoff reveals some rockpool secrets.
BBC Two Scotland
Neil Oliver visits Britain's largest container port.
BBC Two England, Scotland only
Nicholas Crane explores the fishing communities in Scotland. (R)
Nicholas Crane watches the naming of the Royal Fleet Auxiliary's support ship Cardigan Bay
7/13 Neil Oliver joins the crew of the trident submarine HMS Vanguard. (R)
BBC Two England, Northern Ireland (Analogue), Northern Ireland, Wales (Analogue) only
Miranda Krestovnikoff meets the puffins of the Shiant Isles.
BBC One Scotland
Neil Oliver takes the team to Cornwall, England's most coastal county.
Patrick Winterton carried out a 750-mile kayak trip from Glasgow to the Outer Hebrides.
2/2 Neil Oliver revisits some of the defining moments from the two series.
BBC Two England, Wales (Analogue) only