BBC Four HD SkyTV

Alice Roberts swims in cavernous plunge pools, languid rivers and underground lakes to examine the passion for wild water swimming, following the classic swimming text Waterlog. [S] [HD]

3/3. How generals have struggled to kit out their armies for battle. [S] [HD]

2/6. Ben Garrod discovers how the skeleton has adapted for vertebrates to move on land in many ways and explores the role of the spine in both cheetahs and snakes. [S] [HD]

3/4. Timothy Spall and his wife Shane take their barge to three different countries and visit Rafe Spall on the Isle of Man. In Belfast, Tim visits one of his favourite pubs. [S,AD]

A professor develops an extraordinary relationship with an octopus when he invites it to live in his home to learn about its intelligence. [S,AD,SL] [HD]

Programmes start at 7.00pm. [HD]

Programmes start at 7.00pm. [HD]

4/4. Saul David uses the BBC archive to examine the most important stories related to World War II, and how our understanding of them has been redefined since the war ended. [S,AD] [HD]

War drama about the battle for a crucial Rhine bridge in the final days of WWII. Contains language which some may find offensive. [1969] [S] [HD]

A puritan police sergeant arrives on a Scottish island in search of a missing girl, who the Pagan locals claim never existed. Contains some sexual content and disturbing scenes. [1973] [S,AD]

Documentary about cult British horror film The Wicker Man. Featuring actors Christopher Lee, Edward Woodward and Ingrid Pitt, and director Robin Hardy. Deals with adult themes. [S]

7/12. Documentary which looks at why the most inhospitable place on the planet has exerted such a powerful hold on the imagination of explorers, scientists, writers and photographers. [S]