The patent, which cites specific weaknesses in GoPro's cameras, includes details about a camera system that can be mounted on bike helmets or scuba masks, Apple said in an application filed with the U.S. Patents and Trademark Office.
Shares of GoPro, whose cameras can be mounted on helmets, surf boards, bikes and dog harnesses, fell as much as 15 percent.
Apple's newly patented camera system can also be used under water to take pictures and record sounds, according to the application.
A potential entry by the iPhone maker into the action camera market could also put pressure on privately held Polaroid Corp, which makes the small and colorful Cube cameras.
JMP Securities analyst Alex Gauna, however, said it was premature to assume that Apple would soon launch a wearable camera.
"It does not seem to me that launching an action camera accessory is the most logical product extension for Apple to pursue right now," Gauna said.
Apple declined to comment, while GoPro was not immediately available for comment.
"I think that it will have about the same impact on GoPro as the iPhone has had on camera makers and that impact is that there are fewer cameras sold but the number isn't zero," Wedbush Securities analyst Michael Pachter said.
Videos shot with GoPro's cameras have created a buzz on the Internet, attracting millions of views on YouTube.
Olympic gold medal winning snow boarder Shaun White and 11-time world champion surfer Kelly Slater are among well-known athletes who have endorsed the cameras.
Intellectual property blog Patently Apple reported earlier in the day that Apple's patent, which was filed by the company in 2012, incorporates some intellectual property from Eastman Kodak Co that the company acquired in November 2013.
With Tuesday's decline, GoPro shares are now down 51 percent since their high of $98.47 last October. Still, the stock is up 73 percent since its IPO last June.
"We look at it as a buying opportunity at JMP, because what we saw out of the Consumer Electronics Show at Las Vegas last week is that GoPro remains the undisputed leader in the action capture device category," Gauna said.
GoPro shares were down 11.8 percent at $50.10, while Apple was up 1.37 percent at $110.76 in late-afternnon trading on the Nasdaq on Tuesday.
© Thomson Reuters 2015