Two beluga whales from a Shanghai aquarium have taken their first swim in open waters as part of their acclimatisation to an Icelandic sea sanctuary, conservationists said Monday.

Little White and Little Grey, two 13-year-old females, left the Changfeng Ocean World in June 2019 and were flown to Iceland's Klettsvik Bay in the Westman Islands in specially tailored containers.

More than a year later, in August, they were moved from their land-based facility to care pools in the sea at Klettsvik Bay, the first time they had been in the sea since they were taken from a Russian research centre in 2011.

On Monday, the conservation charity Sea Life Trust said the belugas had been "released for the first time to fully explore the natural surroundings" of the wider sea sanctuary at Klettsvik Bay. The sanctuary is a 32,000-square-metre (344,445-square-foot) sea pen that will become their home.

After having been cared for by humans for so many years, it is unlikely the belugas would survive in the wild.

"We are introducing them gradually to the bay in little steps, but seeing them swim together and deep dive amongst the flora and fauna of the wider bay for the first time was amazing to witness and gave us a real sense that Little Grey and Little White are enjoying being back in the sea," Andy Bool, head of the Sea Life Trust, said in a statement.

The belugas will continue to explore the wider sanctuary while returning to the care pools as their health and well-being are monitored on a daily basis "over a short period of time", the charity said.

The whales each weigh 900 kilogrammes (2,000 pounds) and measure four metres (13 feet).

Originally from Russian Arctic waters, it is thought they were two or three years old when captured.

Belugas typically live for 40 to 60 years.

Klettsvik is also where Keiko, the killer whale from the 1993 film "Free Willy", was flown in 1998. The orca was fully released in 2002 but did not manage to adapt to life in the wild and died 18 months later in a Norwegian fjord.