France tests 6,000-meter deep-ocean sensors

France's Ifremer sent two Deep-6000 Argo prototypes through five dives to 6,000 meters between Jan. 11 and Feb. 2. That makes France the third operator, after the U.S. and China, to reach these abyssal depths. The self-diving sensors use layered composite hulls to withstand pressure, pushing past the usual 2,000-4,000 meter Argo range.