Google Earth fills in its watery blanks. Users can explore the sea bed, data on the changing oceans, sea-life and even the best surf spots Google

Since Google Earth launched in 2006 ­millions of people have used its virtual globe to "travel" around the planet without leaving home, climbing a digital version of Mount Everest and even flying into space thanks to the program.

Now the internet company plans to take on one of the last bastions of the unknown: the depths of the ocean.

At a high-profile event in San Francisco, Google is expected to announce the addition of vast amounts of underwater imagery and seabed maps to the Google Earth project.

The move will take Google Earth closer to its aim of creating a complete digital representation of the planet.

The existing site, to which an estimated 400 million people have had access, already includes three-dimensional representations of large cities around the world and includes images from street-level and aerial photo­graphy covering thousands of miles across Britain and elsewhere.

The new additions to the program are expected to include views of the ocean, and portions of the seabed. They will also ­provide detailed environmental data that will enhance information about the effect of climate change on the world's seas and oceans.

To showcase the transformation, the site's chief executive, Eric Schmidt, will introduce dignitaries including the former US vice president and environmental campaigner Al Gore, and the ­veteran ocean­ographer Sylvia Earle, who is an "explorer-in-residence" at National Geographic.

Although, so far, there has been only limited data collected about the sea floor, with just 10% of the habitat mapped at any useful scale for science, bathymetry experts said that the public's ability to "interact" with the oceans and gain better understanding, as well as see the evidence of global warming, could have quite an impact on perceptions.

"This is the part that's really exciting, for me: people will understand that we know almost nothing about a lot of these places, and Google will do it for us," said David Sandwell, professor of geophysics at the Scripps Institute of Oceanography, at the University of California, San Diego. "There are big voids everywhere, but there are a few little spots where we know quite a lot."

The inclusion of environmental information forms the latest part of the company's plan to offer the public more data about climate change. In 2007 Google convened a high-level meeting of experts to help it develop sources of submarine information and environmental data. It seems likely that the company will later unveil partnerships with institutions in Europe and the US as part of the project.

"It's a really useful tool for scientists, to [be able to] share data on the oceans," said Sandwell. "For me, it's the detailed global tectonic structure of the sea floor … if you're a physical oceanographer, the important thing is that the currents and tides are affected by things that stick up from the sea floor."

The development has a less serious side, however. It is also believed people using the site will get the chance to take a virtual dip at some of the world's most famous diving spots, including at sites in the Bahamas, the Red Sea and the Great Barrier Reef.

Despite the project's long gestation, speculation about the precise details has grown since Google announced it would be holding the event. Many observers said they were hoping for something spect­acular. "I don't think this announcement will be confined to just Google Ocean," wrote Frank Taylor, who catalogues the development of Google Earth at gearthblog.com. "When Google makes an announcement like this, they always try to push the envelope on multiple fronts. And, with Al Gore headlining the event, I'm sure we're going to get some data about the environment."

The new system could potentially be combined with another program to let people ­"virtually" move about anywhere in the world.

At the Macworld Expo in January, Google engineers unveiled a program called EarthSurfer, which combined Google Earth with Nintendo's Wii Fit to create an exercise game that allows players movement "around the landscape" by way of balancing on a board. "You control it by leaning forward to go forward, and back to go back," said David Oster, the EarthSurfer programmer on the project at the time. "It's great stuff."

• This article was amended on Tuesday 3 February 2009. David Sandwell is professor at the University of California, San Diego, not the University of San Diego and Google Earth is a program rather than a website. This has been corrected.