“Mind-blowing,” said Zimmerman, who works for Chatham-based Got Stryper Charters and Baits , the company that posted a video of the orca to its Facebook account Sunday.

But there was one marine animal that truly stuck out from the rest: a large orca — better known as a killer whale — that swam in the vessel’s wake for up to 20 minutes, Zimmerman said.

During a 15-hour trip out on the ocean Sunday, Captain Kelly Zimmerman and others aboard a boat that was launched from Chatham saw somewhere around 100 to 150 whales, a few dolphins, and a handful of sharks (one they suspect was a juvenile great white, he said).


“My heart was pounding out of my chest when it came beside the boat,” he said.

He said he didn’t have a charter Sunday, but was out with a group scouting for tuna roughly 70 miles off Cape Cod when the animal showed up. For about 20 minutes, it kept pace with their 36-foot boat, he said.

“They followed our bow wake for about 20 minutes,” he said of the orca and a few dolphins seen in the video footage. “We kept trying to steer away from it and make little course changes and it just stuck right there beneath our pulpit. It was breathtaking.”

Officials from the nonprofit Atlantic White Shark Conservancy shared the charter company’s video to Facebook Monday morning, calling the 22-second clip “absolutely amazing!”

The conservancy said while orcas have been spotted off the Cape before, it is “very rare.”

In 2016, a group on a charter boat 12 miles off the coast of Chatham witnessed a few killer whales swimming near their vessel.

Zimmerman said he’s never seen one of the black-and-white ocean creatures up close before, and he savored the moment while on the boat Sunday.


“I sat down and just watched it,” he said. “We were so close that when it breached and blew out, you could smell the fishy smell — it was wild.”

Steve Annear can be reached at steve.annear@globe.com. Follow him on Twitter @steveannear.