By Brian Dumaine, senior-editor-at-large

FORTUNE — Our thirst for lumber means that each year we lose a swatch of forest about the size of Delaware. Now Triton Logging, based in Victoria, British Columbia, has figured out a novel way to put a dent in deforestation — by harvesting trees not on land but underwater. Until now, logging underwater trees was a dangerous business, with injuries common. But this spring Triton started harvesting ebony, mahogany, and other hardwoods from Ghana’s Lake Volta using its patent-pending SHARC system. SHARC is a barge plus custom excavator with a saw on the end that can find, cut, and retrieve trees at depths even greater than 80 feet, using GPS, video, and sonar. (Watch it at work in the video below.)

The innovation may mean big money: The small private firm, backed by institutional investors, estimates that 300 million trees worth $50 billion lie underwater, mostly in lakes formed when dams were built. That’s true of the Ghana trees, which were flooded during a 1965 dam construction and are worth some $1 billion to $2 billion. (Triton signed a 25-year license with Ghana’s government.)

This article is from the July 25, 2011 issue of Fortune.

[youtube=http://www.youtube.com/watch?v=l2Bl8Yq4sd8&feature=youtu.be]

Editor’s note: A previous version of this story included a caption that mistakenly said that the image above was of Lake Volta in Ghana. The image is of Lois Lake in British Columbia.