Image copyright Noel Hawkins Image caption Two members of the Ullapool Sea Savers - Caillin Patterson, 13, and Maia Patterson, 10 - with the robot

A children's conservation group has helped to reunite a "lost" underwater robot with its owners.

Scientists had deployed the machine called a glider to gather data on Atlantic ocean currents.

But after completing its months-long mission off the Western Isles it lost power.

The crew of a Spanish fishing boat picked it up and it was dropped off at Ullapool where Ullapool Sea Savers then posted a photograph of it on Twitter.

The conservationists' post was spotted by the Scottish Association for Marine Science (SAMS) in Oban, whose scientists had deployed the National Oceanographic Centre robot.

SAMS said it was delighted to have the glider, named Denebola, back.

The robot was deployed in June last year between the isles of Barra and Coll.

It journeyed to a location in the north-east Atlantic and made 1,030 dives to depths of 1,000m (3,280ft).

'Swirling eddies'

The glider was returning to where it could be collected when it lost power in strong currents last month.

It was picked up by the fishing boat on 2 December and this week dropped off in Ullapool.

Ullapool Sea Savers were visiting the harbour with Noel Hawkins of the Scottish Wildlife Trust at the time.

Mr Hawkins said: "We heard a Spanish fishing boat was unloading and had brought ashore an item of interest.

"We went for a look and discovered what we thought was an underwater drone of some sort. After seeing contact information on it for the people at the National Oceanographic Centre we posted on social media about the find."

The Sea Savers were quickly contacted by both SAMS and the centre, and given information about gliders and the missing Denebola.

More missions planned

Dr Emily Venables, of SAMS, said: "There are big currents and swirling eddies of water in the north-east Atlantic, which the gliders can sometimes struggle to make progress against.

"The pilots tried hard via satellite communications to guide Denebola around them, but she repeatedly got pushed back west, draining a lot of power from the battery on each attempt."

Fortunately the "huge amount" of data the glider had gathered was safely backed up. SAMS was also able to track the robot even after it lost power.

Dr Venables said: "Although we already had the data safely backed up, we did not want to lose her, as there are more missions planned for her in the future, so we are very grateful for the assistance we got in retrieving her from the water.

"On this particular mission, Denebola was collecting hydrographic data for a long-term time series monitoring ocean currents. These currents supply heat to the Arctic, and are part of the global ocean circulation that our climate is so dependent on."