It wasn't the most elegant way of getting close to Mexican nature, but boy, was it relaxing. With my legs through the arm holes of a lifejacket, making it into passable imitation of an armchair, I was being propelled by a gentle current down a canal that had been dug by the Mayans a millennium earlier.
The water was the temperature of a pleasant bath and clear enough to see shoals of small fish. On either side, mangrove trees - robot-like with their arching tubular roots - were decorated with brightly-coloured and very vocal birds.
Zopilotes, a kind of vulture, cruised overhead, but the crocodiles (the only local beasts worth worrying about) were a good few kilometres away, on the coast. And, in any case, when the 45 minutes of floating was over, there was a motorboat waiting to speed me and other members of my tour group back across two turquoise, freshwater lakes to terra firma.
We were in the middle of a huge protected area: the Biosphere Reserve of Sian Ka'an, just below Mexico's Riviera Maya on the Caribbean coast of the Yucatan Peninsula.
A mere 200km to the north is the mega resort of Cancun, which is as close as you can get to Las Vegas-on-Sea in this part of the world. The journey from there to the almost shocking contrast of this wilderness entails a drive down the coastal road (the N307), passing hotel developments, the mushrooming resort of Playa del Carmen and a clutch of Disney-like water parks.
Finally, beyond the low-key town of Tulum, with its spectacular cliff-top Mayan ruins, you reach Sian Ka'an.
In the language of the original Mayan people, this means: "Where the sky is born" or, even more appropriately: "Where Heaven begins".
The reserve, 120km long and 50km wide, is a Noah's Ark of southern Mexico's flora and fauna, for which it has been recognised as a UNESCO World Heritage Site.
Its mix of tropical savannah grasslands, tropical forest and lagoons shelters the region's five big cats - jaguar, puma, ocelot, margay and jaguarondi - as well as howler and spider monkeys, four kinds of turtle, crocodiles and manatees. Not that we had got up early enough to see most of those.
I'm afraid the only four-legged animal we'd spotted was a scrawny black cat, which nevertheless was eagerly snapped by most members of our expedition. We'd been luckier with birds: Eduardo our guide, a biologist with a particular interest in migratory animals, had pointed out egrets, an ibis, yellow king birds and a very noisy brown jay. But this is just scratching the surface of the bird-life in Sian Ka'an: around 350 species have been spotted here, including the gorgeous, rainbow-hued mot-mot and the massive but very rare, jabiru stork.
The tour had started at Muyil, a right turn off the N307, 15km south of Tulum. This is one of the five entry points to the park and the one that is generally least used. The forest is higher than in most of the Yucatan, where scrubby bush is the norm, but even here the soil is very shallow, supporting a relatively small number of varieties, such as palms, fig and acacia.
We passed a Zapote or Sapodilla tree, the resin of which was once used to manufacture chewing-gum (the trunk still bore the scars left by resin-collectors). Another tree, the chechen or black poisonwood, was recognisable from its shiny, curvaceous leaves, but should never, however, be touched. Its sap causes an irritating skin rash.
The greatest threat to visitors, according to Eduardo, is posed not by poisonous trees, nor by one of the four species of venomous snake that are found in the reserve, but by falling trees and branches.
A huge crash from the forest nearby, as a tree gave up the struggle to stay upright, underlined his point. Like much of the Yucatan, the forest was at one point inhabited by large numbers of Mayans and Muyil has a number of reminders of their once all-powerful civilisation, including a stretch of one of the raised, paved roads or sacbes which, a thousand years ago, linked the major Mayan settlements.
The tallest and most striking building is the 20m-high castle, El Castillo, although the so-called "Pink Palace" is interesting for its vestiges of the coloured stucco that originally covered all the Mayan buildings.
The descendants of these people, whose civilisation had already collapsed before the arrival of the Spanish conquistadores in the 16th century, still eke out an existence in the vicinity of the ruins. About 600 Maya are reckoned to live within the boundaries of the reserve. The regional government encourages them to supplement subsistence farming and fishing by engaging in the tourist economy, just as the vast majority of their compatriots on the Riviera Maya do.
The motorboats that whizzed us across the lagoons, for instance, were owned by a co-operative from the local village of Chunyaxche and a recent project to teach some of the younger men English by bringing in several blonde, female English teachers had achieved, perhaps unsurprisingly, a good degree of success.
In the next two years, expect plenty more attention on this part of the world. Not so much because British Airways is stepping up its flights from Gatwick, more that the end of the world is nigh - at least according to an unholy alliance of New Agers and Hollywood producers.
The film 2012 is based on the premise that the Mayan calendar predicts a cataclysm taking place two years from now, on 21 December.
In fact, this merely marks the start of a new round in one of the remarkably sophisticated calendars that have endured for centuries.
So, if you plan a trip starting two years today, go ahead - the massive hotels of Cancun will still be standing, along with El Castillo.