Eco- is a prefix used loosely by the travel industry. On Mexico’s fast-developing Caribbean coast, for instance, the giant new holiday complex Mayakoba calls itself an “eco-benchmark against which all future developments will be judged”, despite the projected presence of four hotels, containing a total of more than 750 air-conditioned rooms and villas, numerous swimming pools – one hotel, the Fairmont, has five – and a Greg Norman golf course.

It is ironic because this coast is home to some genuinely low-impact if less luxurious hotels: enchanting places such as Villas Delfines on the island of Holbox, where there is a composting toilet – you add wood chips rather than flush – a solar-heated shower in every thatched casita, and windows that are screened rather than glazed. Or Cabañas La Conchita in Tulum, where the solar- and wind-powered electricity is rationed to four hours each evening at a time when most guests are out at dinner.