Completed fully submerged, the mission provides a realistic indication of usable underwater range beyond a straight-line transit figure. Over the course of the profile, the Envoy AUV executed more than 4,000 turns and maneuvers, each of which increased energy demand compared with steady, linear travel. This makes the result a more meaningful demonstration of real-world subsea performance in practical operating conditions.
The milestone was achieved using hydrogen fuel cell technology developed with Infinity Fuel Cell and Hydrogen, Inc., whose fuel cell solution supports Envoy’s long-endurance performance below the surface.
“The significance of this result is not just the distance traveled, but that it was achieved fully submerged in a mission profile that better reflects real subsea operations,” said Neil Manning, CEO of Cellula Robotics. “That is what makes the endurance meaningful for operators, with the potential for fewer recoveries, more continuous operations, and greater efficiency offshore.”
For operators, endurance is what turns technical capability into offshore results. Longer fully submerged missions can reduce the number of recoveries and relaunches required, support mission continuity, and make better use of vessel time in programs where logistics, weather windows, and offshore intervention all affect cost and execution.
The Envoy AUV remained on mission for 385 hours and covered 2,023 km submerged on hydrogen fuel cell power. The result demonstrates persistent, long-range AUV performance in a real underwater operating context and reinforces hydrogen fuel cells as a practical enabling technology for extended autonomous subsea operations.
“We are proud to support a milestone that shows what hydrogen fuel cells can enable in real subsea operations,” said William Smith, President & CEO of Infinity Fuel Cell and Hydrogen, Inc. “This result highlights the role fuel cell technology can play in extending endurance, reducing intervention requirements, and supporting more capable long-range autonomous missions.”
While on mission, Envoy’s hydrogen fuel cell system generated water as a by-product, underscoring the lower-emission potential of fuel cell-powered subsea operations alongside their endurance benefits. The demonstration reinforces Envoy’s suitability for missions where endurance directly affects mission continuity, offshore efficiency, and the practicality of sustained subsea deployment.
