Each year, the Denver Zoo offers several free days to its visitors and in 2017, there are nine of them. Admission will be waived to all zoo-goers on January 12, 20, and 21, February 2, 12, and 13, as well as later in the year on November 3, 6, and 16. On all of these dates, the Denver Zoo will be operating under winter hours, with gates opening at 10 a.m. and closing at 4 p.m., and grounds shutting down completely at 5 p.m. No monkeying around – this amazing opportunity can save families anywhere from $9 to $13 per person, so be sure and mark your calendars!