Crew members on a whale-watching boat recorded video of the pair in about 100 feet of water near Salt Creek Beach in Dana Point on Tuesday.
Capt. Frank Brennan aboard Dana Wharf's Ocean Adventure estimates the calf was just a day or so old.
As the baby and mom were heading south, a few dolphins and sea lions also got in on the fun and checked out the whales.
Several other gray whales have also recently spotted off the coast of Camp Pendleton.
The Associated Press contributed to this report.