The blue twilight -- Your mission -- Fishing the depths -- Dawn descent -- Getting darker -- Getting colder -- Coming up -- Microscopic life -- Marine snow -- A deep-sea vampire squid -- The deep scattering layer -- Rise and fall -- Big-eyed hunter -- Top predators -- Mirrors and light -- Deep water-giants -- Talking whales -- Heading south -- Deep currents -- Diving with elephant seals -- Mission debriefing.