"I was just like, man this is it, like I'm probably not going to make it," he recalled to ABC News.
The tourist from America was with his partner and two friends when the incident began.
"We were kind of just eating tacos and that's when I started hearing gunfire," he said.
The gunmen headed ashore in front of a Hyatt Resort just south of Cancun and opened fire.
MORE: Masked drug gang gunmen storm beach, execute 2 in front of Cancun-area resorts
The shooting left two dead and four Americans injured. The armed suspects initially escaped, but local authorities confirmed to ABC News on Friday that they have five people in custody.
"We thought that they were fireworks and then more started going off and everyone started to panic and run," Vanvalkenburg said. "That's when I took off and all of us jumped into the pool."
The mele sent tourists scrambling for cover as some hid under pool chairs.
"Right when I jumped into the water, I went to dive and that's when the bullet hit. And as soon as the bullet hit me, I came up ... and I was holding the gunshot wounds as I was bleeding, kind of putting as much pressure as I could because I knew that I had just been hit," Vanvalkenburg explained.
"I honestly thought that I was gonna die because I thought the gunmen were going to basically come and just kill everyone [who] was there at the resort," he said.
Vanvalkenburg was taken to a local hospital and later released.
Hyatt told ABC News "the safety and wellbeing of guests and colleagues is always a top priority."
Now as he recovers back home in Utah, Vanvalkenburg said this incident has left him reconsidering how he travels.
"I never in a million years thought that I would have to worry about my life sitting in a resort," he said. "So it's going to be very different now if I travel again."