What’s the safest swimsuit color? Skip blue and black.

Popular Science...

A pleasant swim at the beach or pool can quickly turn deadly. Every year, over 4,000 people die from unintentional drowning across the United States.

Swim safety experts say drowning is highly preventable. They recommend learning basic swimming skills, designating “water watchers” to keep an eye on children in the water, and avoiding swimming alone or under the influence.

But what if your outfit could stop you from drowning? Swim safety experts say wearing the right color on your next beach day is a good way to stay visible and out of harm’s way—especially for inexperienced swimmers and kids.

So what are the safest swimsuit colors?

Lisa Zarda, Executive Director of the U.S. Swim School Association, says people wearing bright, neon colors are easiest to spot in pools, lakes, and oceans, while blue, black, white, and gray swimsuits blend into the water.

“When the water is moving and reflecting the sunlight, certain colors just disappear under the water,” she said. “Especially in open water, where it can be kind of murky and hard to see: The brighter the color, the better.”

Wearing bright colors helps lifeguards and other safety officials identify and rescue people who are at risk of drowning. Vivid orange and super-bright, highlighter yellow are two standout colors for swim safety.

“Think safety vests and traffic cones,” Zarda said. “Those are bright colors also for a reason—so that they can be easily seen.”

An informal study by Alive Solutions, a public safety group, tested swimsuit visibility in three different conditions: in a pool with a standard light bottom, a pool with a dark bottom similar to dark blue ocean environments, and in an outdoor lake with brown-gray water.

Across the board, the study identified bright, neon orange as the most visible color. But there was some slight variation of which colors stood out best in different environments. Against a dark pool bottom, neon yellow, green, and orange were the most eye-catching, while even brighter reds and pinks appeared darker, and both light and dark colors faded into the water.

In a pool with a light bottom, most colors stood out, while light colors like white and light blue disappeared almost instantly.

In a lake, only neon colors were visible while all other colors quickly blended. So bottom line: stick to a neon orange swimsuit if you want to be sure to be seen.

Boy in dark blue swim trunks standing on jetty on a lake. — Dark colored swimsuits can be especially hard to spot in open water. *Image: mrs / Getty Images /* MARTINS RUDZITIS

What makes neon stand out?

All visible color is the result of reflected light. A red apple, for instance, absorbs many wavelengths along the light spectrum, but bounces back red wavelengths. So to the human eye, an apple appears red.

Ordinary colors, like the red of an apple, only reflect the light they receive, but fluorescent pigments do more than that. They also absorb incoming nonvisible ultraviolet and some visible blue light and then re-emit part of that energy as intensely visible light. This is why fluorescent colors almost seem to glow.

Fluorescent shade’s high-contrast is why traffic safety signs, protective gear, and safety and rescue objects, like buoys, are often made with neon materials. It’s also what makes fluorescent swimsuits extra safe.

Swim safety for kids

As summer comes into full swing, Zarda says wearing a neon swimsuit is just one piece of the puzzle to prevent drowning, particularly for kids.

Children are extremely vulnerable to drowning accidents. Kids between ages one to four die from drowning more than any other cause of death, according to the Centers for Disease Control and Prevention. For children aged five to 14, drowning is the second leading cause of unintentional injury.

“Choosing the right swimsuit color doesn’t replace any of the other important layers of protection.” Zarda said.

“Always having undistracted adult supervision, having a fence around your pool, enrolling your child in swim lessons so that they know how to swim and navigate in the water—those are all still very important.”

In Ask Us Anything, Popular Science answers your most outlandish, mind-burning questions, from the everyday things you’ve always wondered to the bizarre things you never thought to ask. Have something you’ve always wanted to know? Ask us.