David Attenborough narrates this BBC/Discovery program that travels around the globe to reveal never-before-filmed and never-before-seen life and behavior from beneath the seas.
Titles include:

Seasonal Seas
There are some seas where fish swarm in millions and plankton blossoms in vast clouds. The quantity of life here is unmatched anywhere in the oceans. Bordering the temperate parts of the world, where conditions change throughout the year, these are the most productive seas on Earth.
Coral Seas
Bathed in warm, clear tropical waters, coral reefs are the rainforests of the sea. They look like underwater paradises, but life is actually spent in a fight for the best space where corals hold everything together.