Two and a half years ago, the software engineers behind Google Earth, the searchable online replica of the planet, were poised to fill an enormous data gap, adding the two-thirds of the globe that is covered by water in reality and was blue, and blank, online.
But until then all of the existing features on Google Earth — mountains, valleys, cities, plains, ice sheets — were built through programming from an elevation of zero up.
“We had this arbitrary distinction that if it was below sea level it didn’t count,” recalled John Hanke, the Internet entrepreneur who co-created the progenitor of Google Earth, called Keyhole, and moved to Google when the company bought his company in 2004.
That oversight had to be fixed before the months and months of new programming and data collection could culminate in the creation of simulated oceans. On Monday, the oceans will be the most significant of several upgrades to Google Earth, with the new version downloadable free at earth.google.com, according to the company.
Another feature, Historical Imagery, provides the ability to scroll back through decades of satellite images and watch the spread of suburbia or erosion of coasts.
Click a function called Touring and you can create narrated, illustrated tours, on land or above and below the sea surface, describing and showing things like a hike or scuba excursion, or even a research cruise on a deep-diving submarine.
The two-year push to fill in the giant blue blanks came through a chance encounter in March 2006. Mr. Hanke was poised to receive an award from the Geographical Society of Spain for his pioneering work building Web-based models of the planet.
But he was preceded at the dais by Sylvia Earle, a former chief scientist at the National Oceanic and Atmospheric Administration who was there to receive her own award for deep-sea exploration and popularizing ocean science.
She turned to him and said she loved the way Google Earth allowed users to see how one thing relates to another on the planet. But Dr. Earle bluntly added: “You’ve done a great job with the dirt. But what about the water?”
Since that time, Dr. Earle and Mr. Hanke have been partners in the long effort, as she explained, “to make sure the mountains don’t end at the beach.”
“I’ve been struggling my whole life to figure out how to reach people and get them to understand they’re connected to the ocean,” Dr. Earle said.
“But I go to the supermarket and still see the United Nations of fish for sale,” she said. “Marine sanctuaries are still not really protected. Google Earth gets all this information now and puts it in one place for the littlest kid and the stuffiest grownup to see in a way that hasn’t been possible in all preceding history.”
By choosing among 20 buttons holding archives of information, called “layers” by Google, a visitor can read logs of oceanographic expeditions, see old film clips from the heyday of Jacques-Yves Cousteau and check daily Navy maps of sea temperatures.
The replicated seas have detailed topography reflecting what is known about the abyss and continental shelves — and rougher areas where little is known.
With only 5 percent of the ocean floor mapped in detail, and 1 percent of the oceans protected, Google executives and the marine scientists who helped build the digital oceans said they hoped the result would inspire the public to support more marine exploration and conservation.
During a recent test drive of the new features at Google’s San Francisco office, I swooped in over Hawaii and dived beneath the undulating wave-dappled surface of the Pacific to explore canyons, reefs and other features that are now charted precisely everywhere that government data exist.
I also revisited Greenland, the North Pole and Alaska’s North Slope. And, in less than a minute using the Touring feature, I created a rough narrated travelogue retracingreporting assignments in the Arctic, dropping in YouTube videos for any visitor to view on location.
By hovering over Galveston, Tex., clicking on a pointer and sliding it forward along a bar reflecting years of data, I was able to watch seaside communities expand and then abruptly wash away after Hurricane Ike.
The feature powerfully conveys the increasing interplay of humans and the environment, for better and worse, as populations grow and spread.
The addition of the oceans posed many technical hurdles, not the least being aligning disparate data sets so water meets land in precisely the right places, Google engineers said.
Other snags will almost certainly pop up as millions of users scour the new terrain.
But many of the ocean scientists who quietly worked with Google over the last two years to pull together vast data sets are elated at the prospect of the seas’ getting new visibility, and respect.
“It’s a way of raising awareness from thousands to billions overnight,” said Richard W. Spinrad, the N.O.A.A. assistant administrator for research, who served on an advisory panel.
Barbara Block, a Stanford University biologist whose tagging projects have helped clarify the hidden lives of bluefin tuna, great white sharks and other depleted species, said the blue side of Google Earth could also increase public support for marine conservation.
“We cannot as a community conserve what we cannot see,” Dr. Block said. “We’ve worked with the Monterey Bay Aquarium for years to put giant bluefin and white sharks on display, and if we’re lucky two million people a year come and see the animals and discover their color, beauty of motion and form. With the Google oceans feature, we potentially can reach hundreds of millions.” And, said Peter Birch, product manager for Google Earth, the presumption is that wherever lots of eyeballs and mouse clicks land, there is sure to be advertising revenue. In the three years since its public unveiling in 2005, Google Earth has become a mainstay of students, travelers, businesses and researchers seeking a one-stop place for posting or finding information about the world — on topics as diverse as hotels and hiking trails, species’ ranges and climate data.
In that time, the software package has been downloaded on half a billion computers. Visitors spend one million hours a day perusing Google Earth and the related Google Maps.
Some commercial Web sites, includingshipwreckcentral.com and wannasurf.com, have already been actively promoting ocean activities and will now enable divers or surfers to add their own narrated, illustrated “tours” of favorite reefs or beaches to Google Earth’s layers.
Organizations seeking to reconnect people directly with nature expressed guarded optimism when the new features of Google Earth were described.
“Electronic images can boost awareness and sometimes even inspire, but there’s no substitute for direct experience in nature,” said Cheryl Charles, the president of Children and Nature Network, which seeks to end what it calls “nature deficit disorder” in modern plugged-in society. “Hopefully those exploring Google’s virtual oceans, especially children, can still find the time to get wet, as well.”