Xochimilco

The Alcaldía de Xochimilco sets and publishes the rate: MX$750 per hour, per trajinera, at every authorised embarcadero, for anything from one passenger to eighteen. It is not a per-person price, it does not change with the day of the week, and it does not change because your group is small. The borough repeats this in its own public notices precisely because visitors are quoted otherwise.

How it goes wrong. First, per-person quoting — someone offers 'MX$200 each' for a group of six, which is MX$1,200 for a boat that costs MX$750. Second, the hours: agree the number of hours before you step on, because a two-hour ride quietly becoming three is the commonest complaint. Third, the touts on the approach roads who intercept cars and walk-ups before the pier — they are selling access to something that has a fixed price fifty metres further on.

What is legitimately extra: food and drink bought from the boats that pull alongside; a mariachi or marimba group, which is negotiated per song and typically costs more than most people expect; and parking at the pier if you drive. Agree those prices before the service starts, in pesos, out loud. Cash is what everything here runs on.

The borough's own listing splits them: the historic tourist embarcaderos, which are busy, loud and full of food boats, and the ecological ones, which run into the protected wetland where the chinampas are still farmed.

If you want the postcard — painted boats three abreast, marimba, beer, families — go to Nativitas on a Sunday. If you want the reason UNESCO listed the place, go to Cuemanco or Fernando Celada on a weekday morning and ask the poler for the chinampa route rather than the party circuit. Both cost MX$750 an hour.

The chinampas are artificial islands built up from lake mud and staked with willows, farmed continuously since before the conquest and still producing flowers and vegetables for the city. From the water you pass greenhouses, small landings, dogs, plant nurseries selling cempasúchil marigolds by the hundred before Day of the Dead, and long straight channels that look like canals because that is exactly what they are.

The Island of the Dolls

The Isla de las Muñecas, hung with weathered dolls by a caretaker who died in 2001, is deep in the ecological zone — a genuine two to four hours each way from the main piers, not a stop on an ordinary two-hour ride. Boats advertising it from the tourist piers usually go to a nearer imitation. If it is the reason you are coming, budget the whole day, leave early from Cuemanco, and agree the hours and the price before you set off.

The axolotl

Xochimilco is the only place on earth where the axolotl lives wild, and it is critically endangered — you will not see one from a boat. What you can do is visit one of the chinampa research stations that keep them, which some ecological routes include; ask when you agree the route rather than expecting it.

Sunday afternoon is the full experience: hundreds of boats, families, floating kitchens, marimba and mariachi boats working the traffic, and a crush at the pier. Saturday is nearly the same. Weekday mornings are the opposite — half a dozen boats on the water, herons, the sound of the pole in the mud, and the farmers actually working. Both are worth doing; they are not interchangeable.

Seasonally: the rains from June to September arrive in the afternoon, and a covered trajinera in a downpour is atmospheric for ten minutes and cold after twenty — go in the morning in those months. Late October and the days around 1 and 2 November bring Day of the Dead night rides and the marigold harvest, which is the most beautiful time to be here and the busiest. Bring a layer whatever the month: the water is cool and the wind picks up at dusk.

From the Centro Histórico allow an hour to ninety minutes. The public route is Metro Line 2 to Tasqueña and then the Tren Ligero to Xochimilco, which puts you a fifteen-minute walk or a short taxi from Nativitas; Metro is MX$5 a trip and the Tren Ligero MX$3 on the operators' published tariffs. An app car from Coyoacán takes about 30 minutes, from the Centro about an hour in traffic, and is the sensible way back if you finish after dark.

Driving is fine on a weekday and unpleasant on a Sunday; the piers have paid parking. Whichever way you come, the classic pairing is Coyoacán in the morning — the Casa Azul if you hold a slot — and the canals after lunch, which is how the three-day itinerary builds the southern day.

Morning in Coyoacán — the Casa Azul if you hold a slot, the market for lunch — then the canals from about two. Two hours on the water puts you back on dry land by five, before the rain in season and before the traffic north hardens. That is day three of the three-day itinerary.

If you are only here for a weekend, this is the one thing on the list that is not a museum, and that is an argument for keeping it. The rest of the trip is on the independent Mexico City guide.