Pack for Cancun the way the weather behaves, not the way the brochure looks. It sits at around 88F from May through September with humidity in the seventies, and it rains hard in short bursts most afternoons in the wet season. That means the only clothes worth suitcase space are ones that dry fast, do not cling, and read as finished without an iron. In practice: cotton, linen, light silk and jersey in cuts that skim rather than grip. Everything below is built around a week-long trip where you swim at least once a day, eat dinner somewhere with a dress code, and walk on sand, tile and cobblestone in the same afternoon.

The structure that works is roughly four dresses, two swim sets, two flat pairs of shoes and one bag that survives sunscreen. Four dresses sounds thin until you realise a cotton maxi is a beach cover-up at noon and a dinner dress at eight with different shoes. Skip anything that needs a bra you would not swim in, anything white enough to go transparent when wet, and anything in a fabric that holds heat. Wool, even lightweight wool, is a mistake here. So is a structured jacket you will carry rather than wear.

Fabric does most of the work. Cotton and linen breathe and dry quickly, and they look better creased than polyester looks pressed, which matters after a day of sitting on a lounger. Cotton sateen and poplin hold shape well enough for dinner. Fine jersey travels flat, packs into nothing and moves with humidity instead of fighting it. Light silk is worth bringing for one evening, but keep it away from the beach because saltwater marks it permanently.

On fit, aim for a straight or slightly A-line shape with room at the body. Anything bias cut or tight through the hip will read damp all day. Halter and strapless cuts keep your shoulders clear for sun and for the strap marks you will otherwise get from a crossbody bag. On length, a midi is the most useful because it covers enough to walk into a restaurant and still clears the sand.

The practical thing nobody mentions is sunscreen. Chemical SPF stains white and pale cotton yellow over a week, and it will not wash out. Bring one dark or printed piece for the days you apply most heavily, and choose swim in mid tones over white for the same reason. Rinse swimwear in fresh water every night or the chlorine will break down the elastane within a few trips.

Build every day as one dress plus one decision. In the morning, a cotton maxi over a bikini with flat slides is the whole outfit for breakfast, the beach and the walk back. At lunch, the same dress with the bikini swapped for a bra and a belt reads as deliberate. For dinner, change the shoes to a heeled sandal and add one piece of hardware, and you are done. This is why the shoe choice matters more than the dress count.

Two pairs is enough. One flat slide or sandal you can wear wet and walk on sand in, and one heeled sandal for dinner. Braided leather and rope soles handle humidity better than suede, which stains and stiffens. If you only bring one pair, make it the flat, because a heel on tile after rain is genuinely unsafe.

For swim, buy separates rather than a one-piece if you plan to swim twice a day, because you can rotate a dry bottom with a damp top. A balconette or shell top holds up better through actual swimming than a triangle. Bring one one-piece for the day you want to walk into lunch without changing. And bring a bag you do not care about: canvas, raffia or leather you have already broken in, never a light suede or anything you would be upset to see marked.

The mistake we see most often is packing for photographs instead of for heat, which is how people end up with a suitcase full of clothes they wore once. A week in Cancun really does come down to four dresses that work over swimwear, two swim sets you rotate, and a flat sandal you are willing to get wet. Everything else is optional, and most of it comes home unworn.

We would also spend more on the swim than the dresses. Swimwear takes the most abuse, gets worn the most days, and is the thing you notice when it goes slack. A well-cut top holds up through a hundred swims. A cheap one goes in two trips.

If you take one thing away, let it be the fabric rule: cotton, linen and light jersey in mid tones, and nothing that needs pressing or protecting. Get that right and the packing list writes itself.