Sulpam Madeiras Ltda., one of four timber companies operating on the Tucurui lake, began a joint venture with Aquatic Cellulose International Corp. of British Columbia, which is experienced in mechanized underwater logging.

A hundred feet below the surface is a trove of the finest Amazon hardwoods: Brazil-nut wood, mahogany, ipe, angelim, jatoba and, more notable, massaranduba, which is so hard that even iron nails bend when hammered in.

They brought in a $580,000, electronically operated underwater cutting system, expected to start working in July and cut at least three times more trees.

The machine has "arms," equipped with sonar sensors, that embrace a tree, cut it with a chain saw and drag it to the surface. It worked well off the Canadian coast recovering logs already cut, but that area was far smaller than Tucurui.

This article appears to be describing the TigerLynk prototype.

http://articles.latimes.com/2001/jan/06/news/mn-9171