The leader of a dive expedition heading twelve miles off San Diego's shore Saturday stopped just three miles out when she spotted a large fin, only to discover it was a rare whale shark swimming close to shore.
"It really was an experience that took our breath away," said Emily Callahan, an ocean conservationist and diver. "I don't think I'll ever see something like that off of San Diego again, so feel very fortunate that she let us swim along side us for up to an hour, it was really amazing."
Callahan was working as a dive master of SD Expeditions during a shark trip heading 10 to twelve miles off the Mission Bay shore to find mako sharks when she spotted a large fin two feet out of the water.
"I was dying to know what it was," said Callahan, adding that at first the group had no idea what the fin was.
The boat stopped within swimmable distance of the fin sticking out of the water, and Callahan jumped in with her camera.
Callahan is a graduate of the Scripps Institute of Oceanography and runs her own ocean conservation company, Blue Latitudes; once she was underwater and could see the spots of the animal, that's when she knew.
"I could immediately tell it was a whale shark," Callahan said. Of the hundreds of dives she has completed, Callahan said she has never seen something like this.
The shark, swimming in water only 300 feet deep, stuck around for more than an hour. Several other divers on the boat with Callahan jumped in as well, swimming next to the whale shark.
The spotting was a special one because whale sharks are classified as "vulnerable" according to the See the Wild Organization and rarely seen so close to shore.
"To see one up here and have the opportunity to swim with it, that's really cool," Callahan said. "I never would have expected to see a whale shark in California, it's very rarely documented. It does happen, it's just very rare."
Whale sharks are the largest fish in the sea and typically range from 50 to 60 feet in size, according to the Birch Aquarium's website.
"You can't even really compare a whale shark to the Sharks we find off of San Diego. They're just so much bigger," Callahan said.
The "gentle giants" eat zooplankton and are often seen in blue water in tropical seas worldwide. NBC 7 has reached out to Scripps Institute of Oceanography and will update this story when we hear back.
"You never really know what you're going to see in the ocean, and that's what made it so cool," she said.
Callahan said she never felt scared, only amazed, as she swam in such close proximity to such a rare species. "She let us swim along side us for up to an hour, it was really amazing."
"It was pretty once in a lifetime," Callahan said.