A Spanish research vessel that investigates marine ecosystems has been deployed to search for people missing after catastrophic flooding.

The 24 crew members aboard the Ramon Margalef will use its sensors and submergible robot to map an offshore area of 36 square kilometres – the equivalent of more than 5,000 football fields —- to see if they can locate vehicles that last week’s floods swept into the Mediterranean Sea.

The hope is that a map of sunken vehicles could lead to the recovery of bodies. Nearly a hundred people have been officially declared missing, and authorities admit it is likely there are more people unaccounted for in addition to the more than 200 declared dead.

Pablo Carrera, the marine biologist leading the mission, estimates that in 10 days his team will be able to hand over useful information to police and emergency services.

Spain Floods
Residents walk over a muddy street as volunteers work in Massanassa, Valencia (Emilio Morenatti/AP)

Without a map, he said it would be practically impossible for police to carry out an effective and systematic recovery operation to reach vehicles that ended up on the seabed.

“It would be like finding a needle in a haystack,” Mr Carrera said.

Many cars became death traps when the tsunami-like flooding hit on October 29.

The boat will join a wider effort by police and soldiers who have expanded their searches for bodies and the missing beyond the devastated towns and streets.

Searchers have used poles to probe into layers of mud while sniffer dogs tried to find scent traces of bodies buried in canal banks and fields. They are also looking at beaches that line the coast.

The first area the Ramon Margalef is searching is the stretch of sea off the Albufera wetlands, where at least some of the water ended up after ripping through villages and the southern outskirts of Valencia city.

Spanish state broadcaster said on Friday that the body of one woman had been found on the beach after she went missing when the rushing water swept through her town of Pedralba, roughly an hour’s drive from the coast.

Mr Carrera, 60, is head of the fleet of the research vessels run by the Spanish Institute of Oceanography, a government-funded science centre under the umbrella of the Spanish National Research Council.

He boarded the Ramon Margalef in Alicante, located down Spain’s coast, from where it will set sail to reach Valencia’s waters before dawn on Saturday.

The plan is to go straight to work with the 10 scientists and technicians and 14 sailors working non-stop in shifts. The boat also helped research the impact from the lava flow that reached the sea from the 2021 La Palma volcano eruption in Spain’s Canary Islands.

Finding a body at sea is highly unlikely, so the focus is on large objects that should not be there.

The boat’s submergible robot loaded with cameras can dive to a depth of 60 meters to attempt to identify cars. Ideally, they will try to locate licence plates, although visibility could be extremely limited and the cars could be smashed to bits or engulfed in the mud, Mr Carrera said.

In the longer term, he said his team will also evaluate the impact of the flood run-off on the marine ecosystem.

Spain’s meteorological agency said that the 30.4 inches of rain that fell in one hour in the Valencian town of Turis is an all-time national record.

“We have never seen an autumn storm of this intensity,” Mr Carrera said. “We cannot stop climate change, so we have to prepare for its effects.”