Denver Zoo Sea Lion Nick Passes Away During Wait For New Habitat

According to CBS Colorado, Nick—an 18-year-old California sea lion from the Denver Zoo—tragically died on August 7, 2025, at the Smithsonian’s National Zoo and Conservation Biology Institute in Washington, D.C., where he had been staying since 2023 while Denver completed a new sea lion habitat.

Nick was rescued as a newborn on Seal Rock in North Laguna, California, found with his umbilical cord still attached, and was bottle-fed and hand-raised before joining the Denver Zoo Conservation Alliance at just ten months old.

Known for his massive size—over 700 pounds at his peak—and his booming bark, he quickly became a guest favorite for his playful and gentle-giant personality.

In recent weeks, caretakers noticed he was avoiding staff and other sea lions, refusing food, and losing weight. During a veterinary exam under general anesthesia, Nick’s heart stopped and attempts to revive him were unsuccessful. His mate Luci and two offspring, Gunnison and Ady, survive him.

The Denver Zoo’s new habitat, set to open this fall, will feature water-saving filtration systems and more natural environments to enhance animal welfare, aligning with broader zoo sustainability efforts highlighted by organizations like the Association of Zoos & Aquariums.

While Nick won’t get to enjoy it, his story underscores the importance of marine mammal rescue and lifelong care in captivity when release is not possible.

Nick’s life was a testament to what dedicated rescue work can achieve. In his memory, we can choose to protect marine habitats, Support reputable wildlife rehabilitation centers, and embrace plant-based, ocean-friendly diets to reduce human impact on sea life.

Honoring animals like Nick means working to ensure others like him not only survive—but thrive.

This article by Nicholas Vincent was first published by One Green Planet on 15 August 2025. Lead Image Credit :Wirestock Creators/Shutterstock.