- A mineral filter: zinc oxide (Zinc Oxide) or titanium dioxide (Titanium Dioxide).
- No oxybenzone (Benzophenone-3) and no octinoxate (Ethylhexyl Methoxycinnamate). Either one on the list and that bottle stays outside.
- The word "biodegradable" on the front means nothing: in Mexico it isn't a regulated cosmetic certification.
- Turn the bottle around and read the INCI list. That is exactly what the person at the entrance does.
- Turned up with the wrong one? Shower before you go in, cover up with a long-sleeved rash guard, or buy an approved one there.
Why they check
A cenote is underground fresh water connected to a river system that supplies the whole peninsula. It is not a swimming pool: whatever goes into the water stays in the aquifer. That is why the eco-parks here ask for biodegradable sunscreen and, in a lot of cases, make you shower before you get in.
The two ingredients they're looking for
On the label, in the ingredients list (INCI), the two names that get you turned away are:
- Oxybenzone — listed as Benzophenone-3.
- Octinoxate — listed as Ethylhexyl Methoxycinnamate.
If either one is on the list, that bottle is not getting in. It does not matter what the front of the packaging says.
What to look for instead
A mineral filter: zinc oxide (Zinc Oxide) or titanium dioxide (Titanium Dioxide). They sit on the surface of your skin rather than absorbing, and they are what the parks accept.
Every sunscreen here uses a mineral filter and passes that check.
See mineral sunscreensCareful with the word "biodegradable"
In Mexico, "biodegradable" is not a regulated certification in cosmetics: anyone can print it on a bottle. Don't trust the word. Turn the bottle around and read the ingredients list. It is literally what the person at the entrance is going to do.
If you turn up with the wrong one
You have three ways out, in this order:
- Shower thoroughly before going in and don't reapply. Cover up with a long-sleeved top and a hat.
- Buy an approved one at the park shop, which usually costs a good deal more.
- Sort it out before you go.
What almost nobody tells you
Mineral sunscreen has to be reapplied every two hours, and always after swimming or towelling off. One application in the morning does not cover you for a day tour, however high the number on the bottle.
And the sun here works all 365 days: up to 80% of UV goes through cloud, so an overcast day burns you too.
What people ask before they go
Is "reef safe" or "biodegradable" on the label enough?
No. Neither is a regulated cosmetic certification in Mexico — the manufacturer puts it there. The only thing that counts at the entrance is the ingredient list on the back.
Does a mineral filter protect as well as a chemical one?
Yes, and it starts protecting the moment you spread it, with no twenty-minute wait. The price you pay is the white cast.
What if I put it on at home before leaving?
That's why many parks make you shower before going in. Wear the mineral one for the journey — that's when the sun is actually hitting you — and rinse off before you get in the water.
Can I bring insect repellent?
Not in the water, and natural ones are no exception. DEET and citronella are just as much of a problem once they're in there. Put it on when you come out, not before you go in.
See the cenote-safe sunscreens · Find out which one is yours