Marine mammal experts rushed to the shore after the animal was spotted listless in the sand.
"We would have walked right on it," said one eyewitness. "It just blends in so well."
Alameda police stood guard until a marine center volunteer could formulate a plan.
"This is not a good place for him," said Lincoln Shaw with the Marine Mammal Center. "There are lots of dogs, there's lots of people. He needs a place where he can do this molting thing on his own, without being disturbed by humans."
Shaw diagnosed the two-year-old, 225-pound seal as molting and a bit dehydrated. He, or she, simply needed to be sent back out to sea.
"What he really needs to do is find a beach where he can hang out for maybe a week, 10 days, maybe longer and scratch and roll around," Shaw said. "But he's being an elephant seal and he's doing what elephant seals do."
Volunteers placed an orange marking on the seal's back so if he does turn back up again on the shore, volunteers will know who it is.