New archaeological techniques in the deep ocean set an agenda for technology development. In the spring of 1998, David Mindell and his research group built an instrument to project a narrow sonar beam into the seafloor and "see" down into the mud (in technical terms a high-frequency, narrow-beam, sub-bottom profiler). This data, when combined with computerized control and mapping, allow archaeologists to record and replay a "virtual excavation" of a wreck site, that is a three-dimensional model, removable in layers, all in a computer – without ever touching the wreck. (Update 2003: We have updated the sensor with new electronics and signal processing and look forward to the results of our Summer 2003 expedition.)

Sub-bottom profilers have been used for a long time in geology and other oceanographic applications, but usually at comparatively low frequencies (2-20kHz) and with rather wide beams (20-30 degrees). This device has a much higher frequency (150kHz) and a very narrow beam (3-5 degrees). While it doesn't penetrate nearly as deep into the mud as its lower-frequency cousins, the narrow beam allows the instrument to make detailed images which can depict small, buried features.

This device was successfully used for the first time on two Phoenician shipwrecks from the 8th-century B.C. off of Ashkelon, Israel, in June of 1999.  See the story "MIT technology helps map ancient Phoenician shipwrecks" in Tech Talk, July 14, 1999. Also see a National Geographic story about the expedition overall, "World's Oldest Deep-Sea Shipwrecks Found."