The day's adventures conclude as the dives come across some of the planet's most extraordinary creatures. From Monterey Bay, California, Kate Humble presents animals living at the foot of a 2,000m submarine canyon. Off the coast of Costa Rica, Mike deGruy braves a night-time dive into a feeding frenzy of sharks. Meanwhile, off the coast of Mexico, Alastair Fothergill searches for giant, blood-red tube worms. Highlights of today's dives are at 10.55pm.
Director Martyn Suker ; Producer Simon Nash BBCi: digital viewers can access live "first-hand" footage, presented by Peter Snow and Phillipa Forrester , via the red button on their TV handset Underwater wonderland: page 32