You ever get lost and wander into the back areas of a Walmart parking lot?
I'm not talking about the out-of-the-way parking spaces. I'm talking about the areas that Walmart goes to great lengths to hide.
Where the dumpsters are. Constantly leaking a fragrant, brownish goo into a putrid puddle below that oozes along a curb behind it, giving the impression of a mudbank even on the dryest days.
Where bits of plastic and shredded aluminium cans and scrolls of paper and bubble wrap bedeck the shrubs and trees of the surrounding scrub. The staff do their best to keep the area tidy, but minimum wage is not enough to go tramping through the woods like Dr. Livingston collecting stray plastic bags.
Where the fry-oil disposal basins are. Dripping a multihued, swirling slick that is ever-spreading and ever-staining the pavement in a wide circle around it. A circle that turns oddly beautiful in the rain as the patterns expand and combine and move like galaxies across the surface of the water.
And do you know what happens to all those scraps of trash, that rotting oil, that aromatic garbage juice?
Did you say get inevitably washed by the rain to the groundwater in its eternal quest back to the ocean in the water cycle we all learned about in 4th grade?
Then we have a winner! You can pick from the Decepticon pen/pencil eraser or the Bart Simpson toothpaste tube holder.
Now add to all that putrid crap countless gallons of various mechanical oils and jet fuel. And the fry oil and trash of dozens of eateries. And the garbage of duty-free shops getting deliveries of tax-free luxury bullshit every day. All trickling down through rock to the ground water.
Oh... and we haven't even talked about toilet facilities.
The blue dot below is where I turned to the left and took the other picture.
For scale: you can swim from Cenote Caterpillar to Xulo in about 90 minutes. As the crow flies it can't be but a half-mile.
The other picture is of the entrance to the Tulum International Airport. Which is being built... directly over a huge system of underground rivers which are only about 12 feet underground.
Rivers which will wash all that garbage juice and all that fry oil and all that jet fuel right out to the meso-american barrier reef.
Also: How happy would you be if the captain of your flight came on the in-flight speakers to say, "By the way folks, we are about to land a several hundred ton machine today on a runway constructed over crumbly sponge-rock that consistently collapses into the underground rivers 10-20 feet below the surface. Hope our landing gear doesn't get caught in a brand new cenote we create when we touch down. See you at the gate!"
So, my advice: if you haven't seen the Ho Lee Sheet passage in Caterpillar or anywhere in Galaxian you're probably going to want to do that sooner rather than later.
Unless you don't mind jet fuel soaking your dive gear, rendering it wonderfully flammable, to swim through a zero-viz passage a year or two from now.