And the diver had been inside when the animal entered.
Yet what happened beneath the surface was different from what the spectators initially feared.
The diver had found a way out.
Understanding how he escaped requires looking at the expedition, the behavior of the shark, and the unusual sequence of events that transformed a routine wildlife encounter into a remarkable survival story.
Chapter 2: The Great White Sharks of Guadalupe Island
Guadalupe Island lies in the Pacific Ocean, approximately 150 miles west of Mexico's Baja California Peninsula.
Its remote location and surrounding deep waters have made it an important area for observing great white sharks.
These animals are among the largest predatory fish in the world.
Adult great whites can exceed 15 feet in length, with exceptionally large individuals growing considerably bigger.
Their muscular bodies, powerful tails, and specialized sensory abilities allow them to navigate the ocean and investigate potential food sources.
Guadalupe became particularly well known among underwater photographers, marine wildlife enthusiasts, and commercial shark-diving operators.
The island's relatively clear waters offered opportunities to observe sharks moving naturally through the surrounding ocean.
For people interested in these animals, cage diving provided a way to experience their size and behavior at close range.
The protective cages were central to the experience.
A typical shark-diving cage uses a rigid metal framework with bars spaced to permit visibility while restricting access by large animals.
Divers remain inside the enclosure while sharks swim nearby.
The cage may be attached to a vessel or suspended alongside it, depending on the operation and equipment.
Although the arrangement is designed to reduce the risk of direct contact, it still places humans and large wild animals in close proximity.
That proximity matters.
A great white shark does not need to be deliberately aggressive toward a person to create a dangerous situation.
Its size and momentum alone can generate considerable force.
A collision with equipment can cause damage even when the animal is simply moving toward another object.
In the 2016 incident, the diving team was using tuna as bait to attract sharks toward the viewing area.
The bait brought the animals close enough for divers to observe and photograph them.
It also created the circumstances that led to the collision.
One shark approached the bait near the cage.
Its movement toward the food would become the critical event.
The animal was not entering the scene as a predator deliberately targeting a human.
It was responding to a food source.