Logo

Why your sunscreen choice matters in a Mauritian lagoon

Mauritius is ringed by fringing coral reefs and calm, shallow lagoons, and that is exactly why so many British visitors fall for the island. The water sits at around 24–27°C for much of the year, it is often waist-deep for hundreds of metres, and it barely moves. That stillness is wonderful for swimming with small children, but it also means whatever washes off your skin lingers in the same few metres of water where you are paddling. Unlike an open-ocean beach, where currents disperse everything quickly, a lagoon can hold residues for hours.

Add the fact that Mauritius lies close enough to the equator for the UV index to reach 11 or higher between November and March, and you have a destination where visitors apply a great deal of sunscreen, very often. Certain chemical filters, particularly oxybenzone, have been linked to coral damage: they can contribute to bleaching and interfere with reproduction even at very low concentrations. It is not only coral that suffers. Fish, sea urchins and seagrass all share the same water, and marine parks such as Blue Bay on the south-east coast are especially sensitive.

Reading the label: what "reef-safe" really means

"Reef-safe" and "reef-friendly" are marketing terms rather than regulated descriptions. No official standard exists in the UK or the EU, so the logo on the front of the bottle matters far less than the ingredient list on the back. Flip it over and read properly.

• Look for non-nano zinc oxide and non-nano titanium dioxide — mineral filters that sit on the surface of the skin and are not readily taken up by marine life.
• Avoid oxybenzone (benzophenone-3), octinoxate (ethylhexyl methoxycinnamate), octocrylene, homosalate, enzacamene and butylparaben.
• Check for the word "nano". Non-nano means particles larger than 100 nanometres, too big for most coral polyps to ingest.
• Skip aerosol sprays where you can. A good proportion of the product drifts away or lands on the sand rather than on you.

Mineral versus chemical filters in the water

Mineral filters work by sitting on the skin's surface and scattering UV. They begin working the moment they are applied, which suits anyone who forgets to plan ahead, although applying 15 to 20 minutes before you swim is still sensible. Chemical filters are absorbed into the skin and need around 20 to 30 minutes to become fully effective.

The obvious trade-off with minerals is the white cast, particularly on darker skin tones. Tinted formulas solve this neatly, and many brands now offer them. Mineral products can also be thicker and harder to spread, so warm a small amount between your palms and apply in thin layers rather than one heavy blob.

One more thing worth knowing: mineral sunscreens often stay put better in water, but nothing is truly waterproof. "Water resistant" claims are based on tests of just 40 or 80 minutes, so treat them as a guide rather than permission to stay in all afternoon.

Timing, quantity and reapplication

Most people apply roughly a quarter of the amount used in laboratory testing. For the body you need about 30ml — a shot glass — and a teaspoon for the face and neck. In a lagoon you will be in and out of the water constantly, so reapply every two hours, and immediately after towelling dry, even if you have been sitting in the shade.

• Apply on the terrace before breakfast, not on the sand when you are already hot and impatient.
• Swim early morning or late afternoon when UV is lower; midday is the harshest part of the day.
• Build in a shaded siesta between 11am and 3pm. It is the Mauritian way, and your skin will thank you.
• Remember the tops of your feet, the backs of your hands, your ears and the parting in your hair.

Cover up: the simplest eco-friendly alternative

The most effective way to reduce the amount of sunscreen entering the lagoon is to need less of it. A long-sleeved UV swim top with UPF 50+, board shorts and a wide-brimmed hat cover the areas that burn fastest and remove the need to reapply on your shoulders and back. Many swimmers find they then need sunscreen only on the face, neck, hands and lower legs.

Other habits worth adopting: claim a spot under a palm or umbrella, drape a sarong over your legs, wear proper sunglasses, and keep young children in rash vests. They are the hardest group to keep topped up and the quickest to burn, so covering them is far easier than chasing them with a bottle.

What to pack before you fly

Buy before you go if you can. UK pharmacies, supermarkets and outdoor shops stock a wide range of mineral formulas at reasonable prices. In Mauritius, hotel boutiques and pharmacies carry a smaller selection that is often imported and more expensive. Solid sticks and balms are also handy: they rarely leak in a suitcase and take up very little space.

Cabin baggage rules mean liquids must be 100ml or less per container, so either decant into travel sizes or pack sunscreen in the hold. Double-bag anything in a suitcase, as heat and altitude make even well-sealed tubes weep. Take more than you think you need, particularly if you plan to spend long days on a boat or out on the reef.

The reef is the reason the lagoon stays calm, the snorkelling is rewarding and the beach looks the way it does. Choosing a mineral sunscreen, covering up and timing your swims sensibly is a small amount of effort that helps keep the island worth returning to.