I might be missing something, but why is everyone so excited about this? If you want a great experience of the oceans and reefs out there, you could load up an HD video on YouTube of the Great Barrier Reef, and view something much more immersive. I'm a huge fan of street view, and I love being able to virtually drive to where I'm going, and find landmarks to help along the way, like for example, a large orange buildi…
The same can be said for coral reefs, rivers, etc. 'Coral bleaching' is a real problem and reflective of global weather events.
Regarding #2 - In a more idealistic vision of 'Underwater Google Maps', the Voyager Project [1] made an interesting plea to Google to do something similar and provide HD video feeds from UAVs [2].
[1] http://www.underseavoyagerproject.org/
[2] http://www.youtube.com/watch?v=P4iDQsXIi3I
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Edit - Additionally, existing 'undersea documentaries' tend towards visual hyperbole (ooh a yellow fish, damn sharks are scary, etc) - rarely exploring the topography of the ecosystem they're covering. Being able to wander aimlessly underwater may prove more valuable to a student's imagination and provide a more lasting feel for far flung places and culture (or the life of a crab) - as apposed to from a TV, the deck of a cruise ship, or a car window.