This is a sole source procurement for Firm Fixed Price services from BBN for undersea acoustic data collection, processing, and analysis during a scheduled Government Fleet Exercise. The work involves interfacing with the Government’s undersea fiber optic cable architecture at a designated exercise location, with a rapid deployment timeline that precludes other vendors. The amendment changes one task from a base requirement to an option and includes the option-to-extend contract clause. BBN is considered the only source due to existing hardware integration and concurrent activities, as a second contractor would cause logistical interference and unacceptable schedule risks. This notice is not a request for competitive quotes, but responsible sources may submit capability statements for future consideration.