Chase Dekker believes the photo he took of a humpback whale "swallowing" a sea lion is the first time that happening has ever been caught on camera.
The 27-year-old wildlife photographer and marine biologist had taken a boat of whale watchers out on the water in Monterey Bay, California, on 22 July when the incident happened.
"It wasn't a huge group, only three humpback whales and about two hundred sea lions," Chase tells Radio 1 Newsbeat.
"We've seen it all the way up to 100 whales with 3,000 sea lions, so it can get really insane."
The animals were feeding on a school of anchovies at the water's surface when the whale ended up with something a little larger in its mouth than it probably expected.
"We were watching them feed for a long time and then eventually the event - as I call it the once-in-a-lifetime event - happened, and I still can't believe it," he says.
"I had about a split second while the whale was coming up to really comprehend that the sea lion was on top of the whale before shooting the rest of the sequence."
