A New Zealander involved in the search for a missing Argentine submarine says bad weather is hampering rescue efforts.
The San Juan, carrying 44 people, has been missing in the Atlantic Ocean since last Wednesday.
Its exact location isn't yet known, however officials say they've detected noises which could have come from the vessel.
Former Wellington College pupil William Davis is on board the British Royal Navy's HMS Protector, which is part of the search operation.
His father, Miles, has been in contact with his son, and spoke to Newstalk ZB.
"They're all desperate to find the guys and find them alive and help rescue them. At the moment, they're positive and they're thinking positively because that's what you need to do."
Meanwhile, Argentine authorities have analysed sounds detected by probes deep in the southern Atlantic as they search for a submarine that went missing five days ago after reporting an electrical malfunction.
"Special software is being used to study different sounds and acoustics," navy spokesman Enrique Balbi told reporters on Monday.
The probes were being carried out 360km off the coast of Argentina and 200m down.
Balbi said the sounds being detected were "constant", raising some hope the crew of the ARA San Juan submarine might have been intentionally making noise to attract rescuers.
But he said the sounds could just as well be from a natural source.
The vessel, with 44 submariners on board, reported an electrical problem and was headed back to its base at Mar del Plata when it disappeared last Wednesday.
Storms have complicated search efforts.
Hopes for a successful search for the submarine waned when the navy said satellite calls detected at the weekend did not come from the vessel.
More than a dozen boats and aircraft from Argentina, the US, Britain, Chile and Brazil joined the search effort.
Authorities have mainly been scanning the sea from the sky, as storms have made it difficult for boats.
Gabriel Galeazzi, a naval commander, said the submarine had come up from the depths and reported an electrical malfunction before it disappeared 432km off the coast.
One of the crew is Argentina's first female submarine officer, Eliana Maria Krawczyk, 35, who joined the navy in 2004 and rose to become the master-at-arms aboard the ARA San Juan.
Crew members' relatives gathered at the Mar del Plata naval base, waiting for news.
They were joined by President Mauricio Macri: "We continue to deploy all available national and international resources" to find the submarine, he tweeted.
- Additional reporting, Reuters