Cenote etiquette: the rules nobody tells you until you break one

Most cenote rules look arbitrary until you understand that you are swimming in somebody's drinking water. The Yucatán has almost no rivers. Rain falls through porous limestone into a single connected aquifer, and a cenote is a window into it. What goes in the water at one cenote can be drawn from a well thirty kilometres away.

That one fact explains nearly every rule you will meet at a gate.

Shower before you get in

Almost every cenote has a rinse shower and almost every cenote expects you to use it, properly and without swimwear where there is a changing room to do it in. It is there to take off sunscreen, insect repellent, deodorant, hair product and yesterday's sea salt. A rinse that takes fifteen seconds is not a rinse.

Nobody will be rude about it, but staff do watch, and at busier cenotes you will be sent back.

No sunscreen, no repellent — and "biodegradable" is not a free pass

This is the rule people argue about most, so it has its own guide. The short version: chemical filters do not break down in a closed aquifer, "reef safe" is unregulated marketing, and the only reliable answer is to wear nothing on your skin and cover up with a rash guard instead.

Some cenotes sell approved sunscreen at the gate. Most simply expect you to arrive clean.

Do not touch the formations

Stalactites and stalagmites grow at something like a centimetre a century. The oils on your hands seal the surface and stop them growing at all. In cavern and cave cenotes, keep your hands to yourself and your fins away from the ceiling — a single careless kick undoes several thousand years.

Wear the life jacket

At most cenotes the life jacket is a condition of entry, not a suggestion, and at many it is included in the ticket. It is not an insult to your swimming. Cenote water is fresh, so you are less buoyant than in the sea; it is often cold enough to shorten your breath on entry; and in a cavern there is nowhere to stand and no edge within reach.

If a cenote hands you one, wear it. If it does not, look at where you would rest if you got tired, before you get in.

Cash, in small notes

Card payment is rare outside the commercial cenotes and there is no cash machine at the end of a dirt road. Bring more small notes than you think you need — entry, parking, a locker, a life jacket and a snorkel are often four or five separate payments to different people, and nobody can break a 500-peso note at nine in the morning.

Ask before you photograph people, and before you fly anything

Photographing the water is fine. Photographing the family who run the place, or other visitors in swimwear, is not, unless you ask. Drones are banned outright at archaeological sites and restricted at many cenotes; where they are allowed, it is usually at the operator's discretion and outside busy hours. Ask at the gate rather than after take-off.

Leave with everything you brought

There is no bin service at the end of most of these roads. Fruit peel included — it does not compost usefully in a cave, and it teaches the coatis to go through bags.

Two things that are not rules, but should be

Go early. Almost every cenote is calm at opening and busy from eleven, when the tour buses land. The difference between nine and noon at a popular cenote is the difference between two experiences.

Pay the local price if you are local, and the visitor price without complaint if you are not. Two-tier pricing is normal here and it is published openly. The gap funds a place with no marketing budget, run by people who are protecting the thing you drove out to see.