A Seagrass-Planting Robot Just Passed Its First Test on the Great Barrier Reef

The math behind seagrass restoration has always been punishing. Traditional hand-planting methods, when conditions cooperate, can restore roughly five hectares of meadow per year. The Great Barrier Reef contains an estimated 35,000 square kilometers of seagrass habitat, and those meadows are shrinking under pressure from climate change, extreme weather, declining water quality, and coastal development. At conventional restoration speeds, the gap between loss and recovery is essentially unbridgeable.

A partnership between the Great Barrier Reef Foundation, marine robotics company Ulysses, and Central Queensland University is trying to change that equation entirely. During a five-day field trial at Gladstone in July 2025, the team tested an underwater robot named Mako in real Great Barrier Reef conditions, marking the first time robotic seagrass planting had been attempted on the Reef.

The results, announced in February 2026, showed that the concept works. Mako successfully navigated low-visibility, fast-moving waters and planted Nanozostera muelleri seeds into the seabed using small robotic drills that place each seed at the correct depth. The robot can map the seafloor autonomously, identify suitable planting sites, and operate in conditions that would challenge or halt human divers.

The ambition behind Mako is significant. “Current restoration methods, if they go well, restore five hectares of seagrass per year,” said Callum O’Brien, co-founder of Ulysses Ecosystems Engineering. “We’re looking to build a robot that can do five hectares of seagrass restoration per day.” That would represent a thousandfold improvement in speed.

Seagrass may not carry the visual drama of coral reefs, but its ecological role is enormous. These underwater meadows absorb and store vast quantities of carbon, stabilize sediments, improve water quality, and provide food, resting, and breeding habitat for marine species including dugongs, sea turtles, and commercially important fish. On the Great Barrier Reef specifically, seagrass decline has been linked to reduced populations of green sea turtles and dugongs, both of which depend on the meadows as primary food sources.

The trial also revealed areas for improvement. Maintaining consistent seed flow as supplies ran low proved challenging, and the team noted difficulties ensuring optimal planting depth when sediment conditions changed. The modular design of the robot, however, allowed parts to be repaired or swapped in the field, a practical advantage for operations in remote reef locations.

O’Brien described the longer-term vision: an underwater vehicle that can not only plant seagrass but also harvest seeds and monitor restoration sites, “that further drastically reduces the time and cost required and finally makes large-scale seagrass restoration financially viable.”

If the technology scales as planned, it could reshape restoration economics across the Indo-Pacific. The question is no longer whether robots can plant seagrass underwater. It’s whether funding and governance structures can keep pace with the technology.