Protecting your skin from the sun’s UV rays is non-negotiable. But what protects us on land can sometimes create problems beneath the waves.

When we swim, some of the sunscreen applied to our skin washes off and enters the water. And what washes off doesn’t simply disappear. Certain UV-filtering ingredients have been linked to harmful effects on corals and other marine life.

So, before you slather, swim and repeat, let’s take a closer look at what happens when sunscreen meets the sea.

When SPF Meets the Sea

Many conventional sunscreens use chemical UV filters, including oxybenzone and octinoxate, which absorb UV radiation before it can damage our skin.

Great for avoiding sunburn. Potentially less great for marine ecosystems.

Research has linked some chemical UV filters—particularly oxybenzone—to effects including coral bleaching, DNA damage and disruption of coral growth and reproduction under certain conditions. Scientists have also studied their potential effects on fish, sea urchins, algae and other marine organisms.

And because sunscreen enters the ocean alongside other pressures—from warming waters and pollution to coastal development—it becomes one more stressor for ecosystems already under strain.

Why Coral Counts

Coral reefs may cover only a tiny fraction of the ocean floor, but they punch well above their weight, providing habitat for roughly 25% of marine species.

They also help buffer coastlines from waves and storms and support fishing, tourism and the livelihoods of communities around the world.

In other words, coral isn't just pretty scenery for your holiday photos. It's living infrastructure.

When reefs decline, the effects can ripple through entire ecosystems—and reach the people and communities that depend on them.

Your SPF Cheat Sheet

Here’s where things get slightly slippery: “reef-safe” and “reef-friendly” aren’t standardized terms. A pretty ocean-blue label doesn’t necessarily tell you what’s inside.

So skip the marketing shorthand and head straight for the ingredient list.

When possible, choose mineral sunscreens that use zinc oxide or titanium dioxide as their active ingredients. Lotions and creams can also be a better choice around beaches than sprays, which are easier to disperse into the surrounding environment rather than onto your skin.

And remember: sunscreen isn't your only line of defense.

Ditch: Oxybenzone and octinoxate when reef impact is a concern, vague “reef-safe” claims without checking the ingredients, and unnecessary aerosol sprays.

Choose: Mineral sunscreens using zinc oxide or titanium dioxide, lotions or creams and products with clear ingredient labels.

Add: Hats, sunglasses, rash guards, UPF clothing and shade. Less exposed skin means less sunscreen needed—and excellent sun protection never goes out of style.

The Bigger Picture

Some destinations aren't waiting for your beach bag to catch up.

Hawaii restricts the sale of sunscreens containing oxybenzone and octinoxate. Aruba has also restricted certain sunscreens containing oxybenzone, while Palau has adopted broader restrictions on sunscreen ingredients considered harmful to reefs. Some marine parks, resorts and eco-attractions elsewhere have their own sunscreen requirements too.

So if you're heading somewhere tropical, check the local rules before you pack. What’s in the bottle may matter just as much as the SPF number on the front.

The Greenish Guide Take

Protect your skin. Protect the sea. You don't have to choose between the two.

No sunscreen is completely impact-free, and sunscreen pollution is far from the biggest threat facing coral reefs. But choosing your SPF thoughtfully—and pairing it with shade and protective clothing—is one small, practical way to lighten your footprint.

Because the best beach days leave behind only footprints in the sand, not unnecessary ingredients in the sea.