Getcher Motor Runnin

You ever hear the Ballad of Easy Rider? People often associate Steppenwolf’s Born to be Wild with the image of Peter Fonda and Dennis Hopper on their choppers. But the actual theme song of the movie is less aggressive, a proper ballad: peaceful, bucolic, sentimental, peregrine, tragic. The story goes that Bob Dylan wrote the first few verses on a napkin, gave them to Peter Fonda, and told him to give the napkin to Roger McGuinn of The Byrds. The river flows, it flows to the sea

Wherever that river goes that’s where I want to be.

Flow, river flow

It’s a great song. I was humming it to myself through most of the dive yesterday while I was thinking about yet another difference between Floridian caves and Mexican caves. Flow, river flow. It’s been raining a lot here. Like, a LOT. Not just the hurricane triple-header. It’s been warmer than the norm for later than the norm and that has extended the rainy season. So the dirt roads are muddy and there are pockmarked puddles all through the jungle as the water slowly seeps down through the ground into the rivers.

The rivers, you see, are all underground here. There are no surface rivers in the north Yucatan; they’re all underground. The entire peninsula is porous, easily-dissolved limestone. Further, it’s sitting so close to sea level that the ocean can perfuse into the limestone in such a way that, for all practical purposes, the Caribbean Sea is actually right underfoot. An inland sea that is actually “in land.” With the underground rivers sitting right on top, like a freshwater/saltwater parfait. Most divers know the word for this, that interface where the two densities of water are layered with a shimmering optical illusion effect, is “halocline.” When you’re floating above it in the freshwater it looks like there’s a pool of blue water under you. When you’re floating below it in the saltwater it looks as thought there’s a river running across the ceiling above you, eddying around stalactites that poke through it like rocks in a stream. Another thing one notices is that the saltwater doesn’t move. Well… it does. Tidally. Slowly. Moving only through the tiniest of cracks and vugs in the rock in the seawater lens below the peninsula. The freshwater, though… they’re rivers, so yeah, they flow. They don’t flow very hard, though. As everywhere, that rain aggregates into trickles, to rivulets, to brooks, to creeks, to streams, to rivers… all seeking its way, finally, out to the ocean. Difference here is that it all happens underground. And underground it finds the ocean before even bursting forth out into the reef system. When the water hits the halocline it has, effectively, found the ocean. Sea level. Equilibrium. So it’s happy (assuming water gets happy). The limestone, the halocline, the underground rivers… these are key ingredients to the creation of the vast, captivating caves systems that people travel from all over the world to see. Tell a Florian cave diver there is flow in Mexico and they’ll laugh. Usually, rightfully so. There are areas here were there is always strong, predictable flow… but those places are measured in body-lengths. Compared to a place like the Devil’s Ear in High Springs where you have to swim against 30,000 gallons per minute coming through a hole the size of a car door. So yeah, Floridians will laugh. But it has been raining a lot here. With the weight of all that water upstream, the flow here has been higher everywhere. Now, geology and hydrology background covered: the reason I started humming a 60s anthem. In Florida you get really used to flow. You learn how to “read the cave” the same way that kayakers read the river. You know where the water will be moving fastest and where slowest. Though you can’t see them they way you can see rapids, you learn to know where the eddies will be and how to use them to move in the direction you might want to move. In Mexico, by comparison, you don’t. I have frequently seen Mexico-only cave divers struggle and flutter kick and start breathing hard against one of the short stretches where there is flow while I’m off to one side, floating effortlessly in the middle of a lazy eddy. There are benefits to knowing both. This is a conversation I frequently have when people ask, “Where is it better to learn to cave dive?” There isn’t a better - only different. Strengths and weaknesses. In contrast to training in the flow, in Mexico you learn an absolute precision of buoyancy control that can sometimes be difficult to cultivate and maintain in Florida. Because in Florida you’ve always got the flow to mask imprecise buoyancy. You’re always kicking against it, using your body like a wing to maintain position in the water column, or even negative and pulling yourself along the floor. On the way out you’re surfing the river, riding along through the middle of the cave where the flow is strongest, and simply steering to avoid hitting things at a fair clip of speed. In Mexico you don’t have that luxury. You’re kicking the whole way in and kicking the whole way out. Often through fragile clusters of delicate, millennia-old formations that a single stray fin movement will be a wrecking ball against. Unless it has been raining a lot. Only a few minutes into our dive yesterday I turned to Nelly. “A lot of flow today,” I signalled. “I know, right?” Nelly signalled back. The cenote we’d entered was in a bit of a pinch point of the Sac Aktun cave/river system and the passage we were swimming through was a bit off a pinch point of the cave. So… a lot of water trying to get from point A to point B. It still wasn’t Ginnie flow, not even during a drought when the flow is down. But there was noticeable flow. What was even more noticeable: after a few minutes swim we got to an area where the cave opened up and branched off, so the flow suddenly died down. Relieved, I stopped kicking… And started sinking. Working against the flow it had been hard to dial into perfect buoyancy. Without noticing I had fallen into the Floridian habit of masking being a hair negative by using the flow to keep me aloft. I tapped my power inflator to fix myself. And that’s when I started humming the Ballad of Easy Rider.