"You could say our lives are designed around the swimming schedule," says John with a chuckle.
John and Roberta are longtime members of the South End Rowing Club, a San Francisco institution dating back to the 1870s.
On this particular morning, he’s sporting a black speedo, a red swim-cap and bright green fins. She’s in a black one piece and canary yellow cap.
The conditions aren't ideal. A big storm has just blown through, leaving debris, including floating logs, all over the shore and shallows.
With the fast-moving current, John decides to go in backwards. Roberta is doubtful about how easy it'll be to swim back in.
And the water’s chilly, even by these veteran swimmers’ standards, at around 50 degrees.
So for safety, Roberta and John have developed this highly distinctive call and response system.
Listen to John's call here:
Listen to Roberta's call here:
"I call it 'dying seal,'" says John of his wife's call. "But I don’t think Roberta likes that name."
John says his call — which he calls the 'Rebel Yell' — puts him in the fighting spirit.
"It's what the Confederate soldiers used to do before they charged the Union lines," John says. "It's supposed to scare everybody."
Roberta’s call is also wild. But in a different way.
"I didn't pick the seal sound; it picked me," she says. "That's just what came out. And it stuck."
Roberta and John met at the club in the 1980s, and started using their calls soon after they became involved in a clandestine romance.
"Originally, we didn't want people to know that we had made it official," Roberta says of those early days. "So that, I believe, is how we started those calls. They were like a secret code."
They’d use the calls to find out if the other one was around at the club. Roberta would call to see if John was there. And vice versa.
After Roberta and John went public about their relationship, they also started to put their calls to a different use.
"When Roberta and I started swimming together more regularly, it was a good way to signal to each other," he says.
"He'll know by how far away the call is where I am in the water, and know to locate me in the water," Roberta says. "Ditto with John."
Roberta recently had a hip replacement and John has dealt with heart arrhythmia. So their piercing vocalizations can be especially useful in rough conditions.
Like on the morning I meet up with them, about 15 minutes into their swim.
They’ve been keeping up a steady stroke, side by side. But because John’s wearing fins, in no time, he’s pulled far ahead.
Roberta yells “Hey John!” to try to attract his attention. But he doesn't hear her.
She's treading water, trying to figure out which of the several heads bobbing about in the distance belongs to her husband.
"I can't tell which is you!" she says.
It's time to bring out the dying seal. She yells out to John with her signature call. At first, no luck. So she tries again. Then suddenly, bouncing across the waves, comes the Rebel Yell.
John swims towards his wife. They embrace, belt out one last call, and then make their way back to shore.