A self-controlled swimming robot has completed a journey from San Francisco to Australia.
The record-breaking 9,000 nautical mile (16,668km) trip took the PacX Wave Glider just over a year to achieve.
Liquid Robotics, the US company behind the project, collected data about the Pacific Ocean's temperature, salinity and ecosystem from the drone.
The company said its success demonstrated that such technology could "survive the high seas".
The robot is called Papa Mau in honour of the late Micronesian navigator Pius "Mau" Piailug, who had a reputation for finding ways to navigate the seas without using traditional equipment.
"During Papa Mau's journey, [it] weathered gale-force storms, fended off sharks, spent more than 365 days at sea, skirted around the Great Barrier Reef, and finally battled and surfed the east Australian current to reach his final destination in Hervey Bay, near Bundaberg, Queensland," the company said in a statement.
Some of the data it gathered about the abundance of phytoplankton - plant-like organisms that convert carbon dioxide into oxygen and provide food for other sea life - could already be monitored by satellite. However, the company suggested that its equipment offered more detail, providing a useful tool for climate model scientists.
Liquid Robotics still has a further three robots at sea. A second is due to land in Australia early next year. Another pair had been heading to Japan, but one of them has suffered damage and has been diverted to Hawaii for repair.
Each robot is composed of two halves: the upper part, shaped like a stunted surfboard, is attached by a cable to a lower part that sports a series of fins and a keel.
They do not use fuel but instead convert energy from the ocean's waves, turning it into forward thrust.
Solar panels installed on the upper surface of the gliders power numerous sensors that take readings every 10 minutes.
Mixing electronics and water might sound like a risky idea - but Dr Jeremy Wyatt, from the school of computer science at the University of Birmingham, said there was good reason there was so much interest in marine robotics.
"The ocean is a very big place and therefore a safe place to test autonomous robots - these Wave Gliders move slowly and have a low risk of bumping into other objects," he said.
"There are also autonomous sailing competitions in which craft plot their journey completely independently - unlike the Wave Gliders which autonomously follow a prescribed route - and there are a variety of types: robots which bob on the ocean surface, gliders and even fully autonomous submarines which plan their own routes and dive to collect data.
"We are reaching a tipping point in that the technology is becoming so cheap that it's now a much cheaper to use a robot to gather data than to pay for a manned ship to be at sea for months at a time."