Travel underwater and take a look at how scientists used the ALVIN submersible to learn more about sea-floor spreading. **************Related Links************** Oceanography - http://www.britannica.com/eb/article-9056704/oceanography?source=youtube_68437 Seafloor Spreading Hypothesis - http://www.britannica.com/eb/article-9066468/seafloor-spreading-hypothesis?source=youtube_68437 Oceanic Ridge - http://www.britannica.com/eb/article-9056702/oceanic-ridge?source=youtube_68437 Marine Sediment - http://www.britannica.com/eb/article-9050946/marine-sediment?source=youtube_68437 FREE TRIAL - http://www.britannica.com/youtube