PBS Digital Studios has launched a biweekly series called Under H2O, and the first episode is called "The Intertidal." It's only five minutes long, and well worth watching.
'The Intertidal' features rare underwater footage of a part of the marine world that often goes unexplored by scientists and cameramen alike: the intertidal. In this episode, Dr. Musburger and his team take cameras underwater as they sneak into this largely unexplored habitat during the short window of time when the tide is out and tide pools are accessible. With unmatched wave energy, temperature fluctuations, and salinity changes, only the hardiest plans and animals survive.