The new version, launched today at the California Academy of Sciences, takes data from more than 80 organisations, including the US Navy, the National Geographic Society and the Marine Conservation Society.
It provides a map of the underwater sections of the Earth, including mountains, shipwrecks and the deepest part of the planet, the Marinas trench.
"With this latest version of Google Earth, you can not only zoom into whatever part of our planet's surface you wish to examine in closer detail, you can now dive into the world's oceans that cover almost three-quarters of the planet and discover new wonders that had not been accessible in previous versions of this magical experience," said former US vice president Al Gore at the launch.
The software includes up to 21 data points at various points in the ocean, showing everything from surface temperature to information on the underwater environment and images from deep sea surveys.
"Starting today we have a much more detailed bathymetric map (the ocean floor) so you can actually drop below the surface and explore the nooks and crannies of the sea floor in 3D," said John Hanke, director of Google Earth and Maps, in a blog post.
"While you're there you can explore thousands of data points including videos and images of ocean life, details on the best surf spots, logs of real ocean expeditions and much more."
The new software, version 5.0 of the code, also includes the first mapping of Mars, in partnership with Nasa. By selecting the Mars tab users can navigate over the Red Planet using the latest mapping scans from the space agency.
Google has also added a timescale function, so that images on Google Earth can be used to scroll through different eras to see how Silicon Valley grew and matured, for example.
More user information can also be added, including video clips, personal reminiscences and more detailed photographs.