One of the Waikiki Aquarium’s two resident Hawaiian monk seals has died, aquarium officials announced Tuesday.

Maka Onaona (meaning “gentle eyes”), known as Maka for short, died from natural causes on Monday.

He was 34 years old, the equivalent of about 100 years old in human years, the aquarium said.

“We’ve been privileged to have Maka as part of the Waikiki Aquarium ohana since the summer of 1984, when he was brought in from French Frigate Shoals, having been abandoned by his mother at 3 weeks old,” aquarium director Andrew Rossiter said in a news release. “He would not have survived had he not been brought to the aquarium and given special care. As the oldest known Hawaiian Monk seal, his lifespan at the aquarium greatly exceeded the average 17 years of his wild counterparts, and those held in other facilities.

“Maka was an ambassador for his species, and a favorite among our staff and visitors to the Waikiki Aquarium. He will be greatly missed.”

Maka was one of two Hawaiian monk seals previously on exhibit at the aquarium. He weighed only 60 pounds at the time he was brought to the aquarium. As an adult, he measured about 7 feet long and weighed more than 350 pounds. He spent a lot of time spinning upright.

In July, the Waikiki Aquarium reopened its monk seal exhibit following renovations, but Maka did not return to public viewing due to illness. Ho‘ailona, a 10-year-old Hawaiian monk seal with impaired vision, remains on exhibit at the aquarium.