SAN FRANCISCO (AFP) - Online search powerhouse Google has launched a new service to allow Internet users to explore the depths of the world's oceans from the comfort of their homes on dry land. The "Ocean in Google Earth" feature allows users to virtually dive beneath the water surface, explore 3D underwater terrain and browse ocean-related content contributed by marine scientists. Nearly four years after Google Earth enabled users to zoom in to view streets, and later in the sky, the latest version of the software allows virtual travelers to cross miles of unchartered territory underwater. Ocean in Google Earth was unveiled formally at the San Francisco Academy of Sciences by former vice president Al Gore, acclaimed oceanographer Sylvia Earle and Google executives. "With this version of Google Earth... you can now dive into the world's oceans that cover almost three quarters of the planet and discover new wonders," said Gore, a champion in the battle against climate change. Gore pointed out a history feature at Google Earth that lets people see how parts of the planet are changing over time, often due to human influences. "This is an extremely powerful educational tool," Gore said. "My hope is that people around the world will use Google Earth to see for themselves the reality of the climate crisis." Google Earth users can click icons on sea maps to see video of creatures that thrive in those locations. Internet surfers can opt to swim virtually undersea as though they are sharks, dolphins or turtles. Ocean was inspired in part by a teasing comment Earle made to Google Maps and Earth director John Hanke. Earle was at an event when she praised the California firm's online mapping service but suggested it be called "Google Dirt" because it ignored the 71 percent of the planet covered by water, Hanke recounted. "Talk about a dream coming true," Earle said as she stood behind an aquarium lectern and demonstrated Ocean on a large wall screen. "They compressed what it took me 50 years to understand; that the world is really blue. People talk about the world being green, but without the blue there wouldn't be any green." Google Earth users will be able to record videos of undersea adventures, overlay their own voices or sound tracks, and then share them with friends, according to Hanke. Musician Jimmy Buffett, whose hits include "Margaritaville" and "Son of a Son of a Sailor," is collaborating with Google to use Earth and Ocean to let fans travel with him on a coming concert tour starting in the Hawaiian Islands. Buffett joked that he has lived by the bumper sticker motto: "Without geography, you are nowhere." "You will see the travels of Jimmy," Buffett said. "It's fun, but it makes people aware of what we need to do to protect this beautiful planet and its blue heart." By allowing users to explore underwater volcanoes, hunt for whales and learn more about shipwrecks, Google says Ocean offers a platform for everyday Internet browsers to link up with the scientific community. The feature includes 20 different layers of content contributed by leading ocean explorers, scientists and researchers, such as photos and videos of "hot spots" around the world and information on marine protected areas. It also has an animal tracking device in which users can follow animals that have been tagged by satellite. "Oceans cover more than 70 percent of the planet's surface but only a little bit has been explored," said Florence Diss, head of Google's geographical partnerships, referring to findings that humans have examined just five percent of world's seas. Diss added that the decision to expand Google Earth to cover the world's oceans "is not about making money." Diss would not reveal the project's cost. Google employees, affectionately referred to as "Googlers," worked on Ocean as part of a company program that allows workers devote work time to causes about which they are passionate. Google said its updated version of Earth will also take visitors to Mars, using "street view" style images taken by a Rover exploration craft that recently maneuvered about that planet. Since its launch in June 2005, Google Earth has been downloaded more than 400 million times.