In October, while Three Mile Harbor was being dredged by a Suffolk County contractor, Steve Brennan and Chris Martin were using side-scanning radar to follow the course of the dredging work. Side-scanning radar allows one to look sideways along the bottom of a water body and see objects that rise off the bottom such as old wrecks, sunken 55-gallon drums, and other debris. What Brennan and Martin found among other things was a very large boulder in the channel, mostly submerged but sticking up out of the bottom.