Panoramic images of several coral reefs have been added to Google's Street View service in its maps, allowing users to navigate their way around the sites.
The material was gathered by the Catlin Seaview Survey - a project studying the health of the reefs, including the impact of global warming.
The programme's director said the effort would help scientists analyse ecosystems and raise general awareness.
It is also a publicity coup for Google at a time of growing competition.
Google has previously offered computer-generated views of the sea floor terrain, but this is the first time it has incorporated underwater photographs into its mapping product.
"We want to be a comprehensive source for imagery that lets anyone explore anywhere," Jenifer Foulkes, Google's ocean programme manager, told the BBC.
"This is just the next step to take users underwater and give them the experience of an area that most people have been been to - seeing sea turtles, seeing manta rays, crazy pencil urchins and beautiful fish."
Locations added to the service include Australia's Great Barrier Reef near Heron Island, Lady Elliot Island and Wilson Island, as well as Hawaii's Hanauma Bay and Molokini Crater and the Philippines Apo Island.
But while Google's engineers provided technical support to the project, the actual photography and stitching together of the images was carried out by a scientists funded by the Catlin Group, a Bermuda-based insurance firm.
To do so, they developed a submersible fitted with three wide-angle lenses designed to take high resolution images in low light conditions.
The equipment took a 24-megapixel photograph from each lens once every four seconds to provide 360-degree views, as the rig moved over the reef at about 2-3km/h (1-2mph).
"The main reason is to record reef environments on an unprecedented scale and reveal them to the world," explained Richard Vevers, the project's director.
"It's about creating a global reef record - something that has been missing and something that is very much needed. We simply don't have historical records to monitor change on a broad scale.
"Scientists from around the world will now be able to study reefs remotely and very clearly see how they are changing."
Previous studies have suggested pollution, destructive fishing practices and climate change have already caused major damage to many of the colonies of sealife colonies that were built up over thousands of years.
To analyse the new material, researchers at the University of Queensland's Global Change Institute are using image recognition software to identify the creatures recorded in the photographs, and 3D-modelling programmes to monitor how the habitats change over time.
"It's analysing the health of the reef in terms of species distribution, and mapping that against the structure of the reefs to discover what reefs are important," said Mr Vevers.
"When we start working with those two data sets it could prove to be hugely valuable in working out which are the areas that need to be protected."
He added that the survey intended to add images from reefs near Bermuda at a later stage.
The launch provides Google with a fresh opportunity to publicise the range of its mapping products at a time its rivals are gaining ground.
Amazon recently struck a deal with Nokia to use the Finnish company's mapping technology on its Kindle Fire tablets, despite the fact they run on Google's Android software.
Nokia's technology will also be used by Microsoft on its upcoming Windows Phone 8 system.
Apple has ditched Google's service in its default Maps app in the latest version of its iOS mobile operating system.
The move has attracted criticism because of inaccuracies in Apple's replacement service, but has also been recognised as a strategic move that should make the iPhone maker less reliant on its rival.
"We think it would have been better if they had kept ours, but what do I know?" said Google's chairman Eric Schmidt earlier this week in Tokyo.
"What were we going to do, force them not to change their mind? It's their call."
At present they must instead access the product via a web browser if they wish to continue using it.