At first there were only gentle waves. Dolphins cavorted and fed in the shallows. We lay on our backs and let the swells lift and lower us. Only the grandkids invited the breakers to dump on their heads and rollick their bodies.

Then it changed — reported storms out at sea — giving our ocean a wilder face with faster currents and high crests. A red flag flapped in the wind at the lifeguard’s chair as a warning to swimmers. The grandkids, of course, were lured not warned, while grandpa kept watch from the shore’s edge and grandma watched the lifeguard, making sure the lifeguard watched their brood.

“It’s stressful,” they admitted, after settling back down on their towels. They, the grandparents, used to think they were the rescue team, if need be. But no longer. It’s them, the oldies, who need the watching now.

Which is what happened when the children returning to the surf called out, “Come in. We’ve got you.” The grandparents shook their heads and uttered excuses. “Maybe later,” they fudged. Thinking how their balance faltered and their stamina quit. But, the children were insistent doubling down on the pleas to join them. And in the end they won.

Of course, they did. Besides, it was hard not to recall how it once was. How they raced the younger ones into this very ocean, grandpa teaching them the art and challenges of riding waves, employing nature’s own surge. So, they put down their books and took off their sun hats to stand longingly at the edge of the sea.

One after the other, the children emerged from the waves to encircle their elders before they could change their minds. Then one or all uttered the command to run. “Run,” they tugging, assuming a left side guard. “Run,” they galloped, taking the right guard dash.

Run? Run, in truth, no longer part of the grandparents’ vocabulary. Walk fast, shuffle, scurry, but not run. Still at that moment at the command to run, they did, they ran, straight into the ocean. And in no time, there they were, up to their necks to face whatever the incoming surf sent next.

The ocean choreography is all about getting past the breakers. Timing is everything, finding the exact location between swell and breakers before the big ones crash on you. It’s the quiet, the lull before they come in a row of threes.

To the rising and curling of waves comes a great chorus of commands: Dive. Jump. Duck. Swim. And all dutifully dive or duck, jump or swim, swimmers hoping to catch the movement of the wave to ride it into shore.

But not these pummeling waves, which are better off with a dive or dunk. Afterward, there’s the counting of heads: one, two, three, four, five. All heads accounted for just in time for the next round. In time to “dive or duck.”

Over and over, the young ones pumped and powered, disappointed with the lulls, while the old ones are utterly winded. Winded but victorious until enough, they think. Though, that means getting out and the fear that getting out will be their trickiest act yet.

“We’re done,” they admit.

“Wanna get out? We’ll take you,” the grandkids insist. It’s part of their new service to their “fossils,”(affectionately so called). And they do — again the wave brigade. On each side. Ahead and behind as soon as the going is right, when the lull occurs with again the siren cry to “Run!”

And run they do, even when run is not a reliable exertion. But imagining a wave, the one you don’t see, but figure is behind, your old doddering legs are motorized and you go like hell. When run is what you’ve still got to the sing/song refrain of “Keep going, Gram. You got it, Pops.”

And sure enough, grandma and grandpa have got it all the way to where the sand is packed down and the ocean waters are only a frothy trickle, and then it’s only one more wobbling step to the hard-earth reassurance of shore.

“Let us know if you want to go in again,” the grandkids say, making their own way back into the unruly and wonderful waves. And no, their grandfolks won’t go in again. They’ve done it and are ever so grateful for that one more chance to be a younger, bolder self. But then, thank goodness, their beach chairs are waiting.

Ruth Charney lives in Greenfield.