A 26-year-old sea lion at the controversial Mediterraneo Marine Park has passed away.

In a post, the park said: "We are deeply saddened to announce the passing of Dana, one of our long-time residents and beloved sea lions. Dana was a geriatric sea lion who lived at the park for over 26 years. She was born under human care and became a cherished member of the Mediterraneo Marine Park family."

"Recently, Dana developed a lump in her belly, which is sadly not uncommon in elderly Patagonian Sea Lions (Otaria flavescens), whose life expectancy is typically 22-24 years," the Park said on Facebook.

"The park's vet and carers immediately began administering round-the-clock care for Dana and sent a sample of the mass to the University of Camerino in Italy for testing. The results confirmed the presence of a highly aggressive sarcomatous neoplasia, which was unlikely to respond to surgery or chemotherapy."

"Just three days after the official diagnosis was received, Dana succumbed to the illness.

During her final days, we collaborated with international experts in marine mammal care and medicine to ensure her comfort and provide the best medical and pain-alleviating care possible," the park said.

"Malta's Veterinary and Phytosanitary Regulation Division (VRD) was kept constantly updated by the park's vet. Mediterraneo Marine Park extends its heartfelt gratitude to the public for the support and well-wishes we received since Dana's condition was announced last week. Dana will be dearly missed."

The park was under the spotlight recently. Moviment Graffitti, Animal Liberation Malta and a number of other organisations are calling for the closure of the Mediterraneo Marine Park at Nahar ic-Caghaq, following the deaths of three dolphins in 2021, blaming it on the park's "negligence."

The park had said that the three dolphins dying was not the result of mistreatment. It said that as confirmed by the authorities that investigated the case, this was a pure accident. After 25 years in operation, "we had one incident where an external diver cleaning the pools used strictly-forbidden lead weights, which intoxicated the water. This was a huge tragedy for the park," it had said.