Submarines are launched in the first of today's amazing broadcasts from the depths of the ocean. With the help of Kate Humble , Mike de Gruy ,
Alastair Fothergill and Howard Stableford , viewers can follow the progress of the three dives -off the coasts of California,
Costa Rica and Mexico - as the cameras encounter some of the planet's strangest creatures.
More at 5.20pm. www.bbc.co.uk/nature
BBCi: digital viewers can access live
"first-hand" footage, hosted by Peter Snow and Phillipa Forrester , via their TV handset Underwater wonderland: page 32