Over the last few years, technology used to search the bottom of oceans, lakes and rivers has progressed dramatically. One of the main tools of underwater archaeologiests and treasure hunters is called Sidescan Sonar. A vessel will tow the machine on a cable, and it sends back pictures to a computer on board the ship. Like a medical ultrasound machine, Sidescan Sonar takes pictures with sound waves. Marty Wilcox with Marine Sonic Technology says Sidescan Sonar's images keep getting better.