Visitors at the San Diego Zoo experienced a heart-stopping moment on October 14, 2025, when a 10-year-old western lowland gorilla named Denny charged the glass wall of his enclosure, shattering one of three protective layers and sending onlookers scrambling in fear. Eyewitness video of the incident quickly went viral, capturing the dramatic event and the collective gasp of the crowd as the massive animal’s force left a deep six-foot crack just inches from guests.
According to ABC News, the incident unfolded during a typical afternoon at the zoo’s gorilla habitat. The video shows Denny, who weighs up to 500 pounds, suddenly rushing toward the glass, slamming his powerful forearm into the barrier. The impact startled visitors, some of whom screamed and retreated from the enclosure, clearly alarmed by the apparent fragility of the glass that separated them from the powerful primate.
Katja Sutil, a visitor celebrating her birthday with her sister, recounted the terrifying moment in an interview with KSWB/KUSI: “We were looking down at our cell phones and didn’t notice that he had taken a running start, jumped and launched into the glass. He hit it with his elbow or forearm, like right in the glass directly in front of my face. When it hit in front of me, I was so jolted I fell back a few feet. When I looked up to see what had happened, I saw the gorilla staring directly at me, making eye contact with me, and then a giant crack… 6 feet. It was pretty big.”
Sutil’s account was echoed by other witnesses, who described the event as “terrifying.” She added that she and her sister ran away from the exhibit as soon as they saw the crack, not realizing at first that the enclosure glass was composed of three separate layers. “We were really shocked. There was probably a 6-foot crack and the gorilla was just staring at me,” Sutil told The Los Angeles Times. “It was terrifying.”
Zoo officials confirmed in statements to multiple outlets, including The New York Post and KSWB/KUSI, that only one layer of the three-layer tempered glass panel was compromised. No visitors, staff, or animals were injured during the incident, and the enclosure was immediately closed to the public for repairs. Both Denny and the other gorilla present during the event are being cared for behind the scenes while the glass panel is replaced. The zoo has not yet provided a timeline for when the habitat will reopen.
According to a spokesperson for the San Diego Zoo, such behavior is not unusual for adolescent male gorillas. In a statement quoted by The New York Post, the spokesperson explained, “It is common for male gorillas, especially in adolescence, to express these types of behaviors. Bursts of energy, charging, dragging items, or running sideways are all natural for a young male.” Sutil also observed that the gorillas seemed to be taunting each other, adding, “Honestly, the 20 minutes we were there, the gorillas were going back and forth, kind of taunting each other. One would charge the other and then disappear, then it would happen again. So maybe there was tension going on between the two gorillas.”
Before the dramatic charge, Denny appeared to be playfully fighting with the other male gorilla in the enclosure, circling and swiping at each other without making direct contact, according to Sutil’s recollection. This kind of roughhousing, while alarming to visitors, is considered a natural part of gorilla social dynamics, particularly among younger males.
Denny, born at the San Diego Zoo on December 26, 2014, is part of a well-known gorilla family at the zoo. His mother is Jessica, and his father, Paul Donn. Denny has several siblings, including brothers Maka and Mandazzi, and half-brothers Ekuba, Gordon, Gerry, and Bouendje. The family has faced recent tragedy: Maka, Denny’s older brother, died unexpectedly in August 2025 at the age of 30 from cardiac arrest during a medical evaluation. The loss was deeply felt by zookeepers, visitors, and, possibly, by Denny himself. As The Los Angeles Times noted, scientists have observed gorillas expressing grief and exhibiting behavioral changes after the death of a sibling or troop mate—a poignant reminder of the emotional depth these animals possess.
This is not the first time the San Diego Zoo has experienced a gorilla-related glass incident. In 2020, another gorilla damaged a layer of the enclosure glass during a confrontation with a fellow ape. The zoo’s use of triple-layered tempered glass is intended to ensure the safety of both animals and guests, even in the event of such powerful impacts. Adult male gorillas can weigh between 300 and 500 pounds and are capable of lifting up to ten times their body weight, making the structural integrity of their enclosures a top priority.
Western lowland gorillas like Denny are a critically endangered species, native to the forests of Central Africa. Their populations have been devastated by hunting, the illegal pet trade, and habitat loss due to logging and mining. The San Diego Zoo has long been involved in conservation efforts to protect these primates and their natural habitats. Through its African Forest Program, the zoo supports conservation work in Cameroon’s Ebo Forest, a region home to numerous threatened plant and animal species.
The viral nature of the video has sparked widespread discussion online, with some viewers expressing awe at the gorilla’s strength and others voicing concern about the safety of zoo enclosures. While the incident was undoubtedly frightening for those present, experts and zoo officials have emphasized that the layered glass design functioned as intended, preventing any harm to guests or animals. The event also serves as a powerful reminder of the wild instincts and immense physical power that gorillas possess, even in captivity.
As repairs continue and the zoo reviews the incident, visitors and animal lovers alike are left reflecting on the delicate balance between providing close-up encounters with wildlife and ensuring the safety of all involved. For Sutil and others who witnessed Denny’s dramatic display, it’s an experience they won’t soon forget—a vivid illustration of the unpredictable and awe-inspiring nature of the animal kingdom.
