A side-tie tankini by Lands’ End. A tankini is a smarter solution for trips to the beach because there’s less skin exposed to the sun, less re-applications of sunblock, and, most important, no sticky wet one-piece to struggle with during trips to the bathroom.

The tankini bathing suit is a gift to mothers.

There have been other design innovations in recent years that have made family outings to the beach less of a hassle — continuous-spray sunscreen, soft coolers and collapsible camping-style chairs among them — but it’s the tankini that really turned the tide.

At least it’s what has made my life with two daughters much easier.

With a tankini, there’s less skin exposed to the sun, no shifting of the top and, most important, no sticky, wet one-piece to struggle with when the girls have to go to the bathroom.

I’m not alone in my thinking: “I completely agree about separates being the solution for kids,” says Michele Casper, a spokeswoman for Lands’ End.

The traditional tankini is essentially a one-piece bathing suit split into two pieces around the hip.

“There’s coverage, comfort, practicality — and what’s really fun that the kids like is the mix-and-match appeal,” Casper says.

It’s true that my girls, now ages 4 and 7, love to pick their own clothes but don’t always come up with a look that I’d consider coordinated. Tankinis can help with that compromise, too. As long as the top and bottom are complementary (pink and orange are favorites in my house) then I can live with dots mixed with stripes.

Casper says Lands’ End does sell tankinis as a matching set but says it’s quite common to buy two or more and come up with their own combinations.

I’ve even started buying complementary rash guard shirts.

The popularity of those full-coverage, bathing-suit shirts has even turned boys onto at least the idea of a top-and-bottom combination even if it doesn’t fit the classic tankini definition.

Casper says the rash guard is the “hottest trend” in kids’ swimwear.

Rash guards go their name because, originally, surfers wore them to protect their bellies from becoming irritated by their surfboards when they were paddling out, explains Rhonda Sparks, founder of UV Skinz, a California-based company that specializes in sun-protection gear.

They come in short- and long-sleeve versions, and are made of stretchy, quick-dry fabric.

Sparks started making miniature versions of the shirts three years ago after her 32-year-old husband died from skin cancer.

As a couple in the late 1990s, they had started bringing back rash guards for their sons from their annual trips to Hawaii because they were so attuned to the risks of sun damage after Darren Sparks’ initial diagnosis. The three boys have never complained about wearing them, especially now that they’re offered in skull, shark and camouflage motifs, Rhonda Sparks says.

“Usually, kids like them because it means less sunscreen and fewer times being pulled away from their activities to reapply sunscreen,” she says. “If you say you need to come back every 90 minutes to mom or you can wear this, they’re off and running in their rash guard.”

The fact that the same surfers who fueled the graphic T-shirt and board-short trends are among those wearing the shirts should go far in my house as my girls and their friends become increasingly aware of what’s cool. My youngest daughter, a fair-skinned, light-eyed towhead, wore a rash guard shirt with an oversized Hawaiian-flower motif that came with her tankini with great pride last summer — particularly when we’d call her Malibu Barbie.