Colorado's Oldest Zoo Is A Denver Destination Known As One Of America's Most Sustainable

America is home to some of the world's most incredible zoos. California's Sequoia Park Zoo is a fun wildlife haven with a scenic skywalk through a towering redwood forest. Meanwhile, Pennsylvania's Philadelphia Zoo is America's oldest zoo and pushes innovation and conservation. Another zoo, this time on the other side of the country, that's earning high praise for its conservation and sustainability efforts, is Denver Zoo. Dating back over a century, the Denver Zoo Conservation Alliance is Colorado's oldest zoo, and originally started with a single black bear cub.

The zoo's first resident, the orphaned black bear, was named Billy Bryan. He became the first of many creatures, big and small, that Denver Zoo has housed, protected, and rehabilitated since 1896. The zoo is actually a non-profit organization that's entirely committed to caring for its 3,000-plus animals. Since 1996, Denver Zoo has supported over 600 conservation projects around the world, devoting time and money (around $2 million annually) to these initiatives. The zoo has various innovative practices that help care for the animals, including rotational habitat designs that better stimulate animals.

Denver Zoo has also been proactive with its sustainability efforts over the last decade, making considerable headway toward becoming greener. By the end of 2025, it aims to reduce waste by 90% (currently around 76%) and energy and water use by 45-50%. It's also looking beyond 2025 to see how it can continue to improve its sustainability as the goal posts shift with new technology and changes in climate efforts. "We've seen an overall 30% reduction in energy just this past year," said Blair Neelands, sustainability manager at Denver Zoo, in a Visit Denver article. "It's equipment upgrades and automation that [are] really making a difference in that building on energy use."

While some people can find it hard to look at animals in exhibits at zoos, it seems Denver Zoo's commitment to animal care makes it more popular among the masses. With glowing reviews, it's climbing the ranks of the best zoos in America. It's also currently in the top 20 things to do in Denver (out of over 500 sights), with a 4.4-star rating from over 4,000 reviews on Tripadvisor. It also won a Traveler's Choice award in 2025, with many people highlighting the zoo's commitment to animal welfare, particularly its on-site animal hospital that allows visitors to see how the zoo is caring for its residents. 

Other daily demonstrations at the zoo include talks by animal care experts with everything from lions and giraffes to llamas. Kids can also ride on the Conservation Carousel, with every ride contributing money to the zoo's conservation programs. There are over 450 species of animals and birds to witness around the zoo's various themed habitats. The Down Under habitat houses wallabies, cassowaries, and tree kangaroos, while Primate Panorama is where you'll see gorillas and orangutans. Flamingos, sea lions, penguins, elephants, rhinos, and plenty more can be seen most days. You can also get hands-on with stingrays at Stingray Cove, depending on the season.

Denver Zoo is located in City Park. It's about a 15-minute drive from Union Station or around an hour-long commute if you catch bus number 20 and walk a little through the park. Opening hours change throughout the year, but it's generally open from 10 a.m. until 4 or 5 p.m. At the time of writing, general admission costs $26 per person. You can bring your own food or buy something from one of the various cafes and eateries in the zoo.