From the Cape Cod Times: The National Transportation Safety Board found the ship’s wreckage a few weeks after the sinking. In April 2016, with the help of the Woods Hole Oceanographic Institution, it located the voyage data recorder, a device roughly the size of a basketball, in a 13.5-square-mile debris field.
WHOI used two unmanned submersibles, the Sentry and an observation vehicle known as Camper, to explore areas of the wreckage that had a high probability of containing the voyage data recorder. Sentry is designed to produce high-resolution maps of the sea floor; the observation vehicle is a camera sled that provides a real-time video link to the WHOI-operated research vessel Atlantis. Using both vehicles, WHOI investigators were able to first survey the entire search area then methodically hone in on possible locations for the recorder.