Google Maps is officially swimming with the fishes: Street View has partnered with the underwater explorers at the Catlin Seaview Survey to create the world's first high-resolution, interactive panoramas of our most diverse ecosystem: the ocean.
This partnership evolved out of Google's World Wonders project (in which this author participated as a presenter), where Google and UNESCO collaborated to showcase World Heritage sites and other efforts to preserve the world's most unique and treasured places.
From Google's Lat Long blog:

Today we’re adding the very first underwater panoramic images to Google Maps, the next step in our quest to provide people with the most comprehensive, accurate and usable map of the world. With these vibrant and stunning photos you don’t have to be a scuba diver—or even know how to swim—to explore and experience six of the ocean’s most incredible living coral reefs. Now, anyone can become the next virtual Jacques Cousteau and dive with sea turtles, fish and manta rays in Australia, the Philippines and Hawaii.
The resolution is stunning - pop out to full screen to dive right in - and the Street View interface is taken to a whole new level with the granular control to swim at will around some of the world's most diverse underground ecosystems.
Beware: this is a very addictive experience, as there's just nothing quite like it out there. The curious traveler and passionate nature buff will appreciate the immersive 360 degree views of one of the last remaining frontiers.
Catlin Seaview Survey hopes that documenting the world's oceans for everyone to explore will lead us to appreciate the incredible importance they hold for the human race. From their website:

Our oceans feed one in four people on the planet everyday. They produce 50% of the atmospheric oxygen we breathe. They regulate the climate and make our planet habitable. They are integral to our very survival, yet for all of our reliance, they largely remain as they have always done, out of sight and out of mind - 95% hasn't even been seen by human eyes.
Out of the well-trafficked 5%, here are some highlights:
The full Street View gallery of ocean landscapes can be found
here.