If you've never tried to fish a coldwater line in tropical conditions, the idea of needing a line specifically designed for those conditions may seem almost like a gimmick; a ruse to trick you into buying superfluous gear. At least that's how I took it, some 20 years ago, when I headed south for my first tropical fishing trip of any kind. In truth, it wasn't even tropical. I was headed to South Carolina to chase tailing redfish in sweltering, early September heat. The guide I was slated to go out with advised that I bring an 8 weight rod and line and I reckoned, quite reasonably I thought, that the 8 weight setup I'd been using for striped bass off the jetties and beaches of the northeast coast for the prior couple years would do just fine. The rod, of course, did. The line, unfortunately, wilted in the balmy lowcountry water, suffocating humidity and blazing South Carolina sun. Most casts hinged. Those that didn't hung up. Or simply stuck. Casting the line wasn't impossible, but it was three times as much work as it should have been, both accuracy and distance were significantly diminished and, as a result, more than a handful of tailing reds went about their business feeding in the grass instead of getting hooked.
The line was, quite simply, the wrong tool for the job. As it turns out, there's a reason for those specialty fly lines (well, some of them), particularly those made for use in warmer climates and warmer waters. The lines that most fly anglers are accustomed to are designed for cold water, or at least relatively so—water that's most commonly anywhere from 40 to 70 degrees. The coatings and cores in these lines are supple, to prevent the lines from getting too stiff in chillier temperatures. But take these lines to warmer locales, and they turn into limp noodles. This is why lines designed for tropical and other hot environments are designed with much stiffer coatings and stiffer cores. Out of the box in your living room, these tropical lines can seem decidedly too stiff—I can remember thinking I got a bad line the first time I unboxed a tropical line—but take them out in the sun and steam for which they're designed and they soften up and shine.
As noted, these lines are constructed with both stiffer coatings and stiffer cores. While most anglers focus on the former, most line designers will tell you it's the latter, the core, that's the key.
And that's what RIO will tell you about it's new DirectCore Jungle Series fly lines, which are designed not only for balmy tropical conditions, but for tossing big flies to big game fish—like golden dorado, peacock bass, tigerfish, arapaima and other species commonly found in jungle environments. DirectCore, in RIO's case, is the brand's fancy term for a stiff monofilament core, while its other big game lines (such as its Big Nasty series) are built on more supple, braided cores.
While anglers that target those species commonly choose from tropical lines with more delicate tapers—like those designed for bonefish, permit and the like—or big game musky or bass lines that are typically designed for more moderate temperature ranges, the DirectCore Jungle will allow anglers to check both the big game/big fly and hot temps boxes.
According to RIO, the "DirectCore Jungle Series has a powerful front taper and a quick loading head that delivers large flies with exceptional ease and a long rear taper that allows for big mends in moving water. The series is designed to withstand the tropical heat of jungle destinations thanks to a hard, outer coating that is built on RIO’s low-stretch, low-memory DirectCore, which retains the stiffness needed to cast in hot conditions yet lies perfectly straight on the water."
RIO's DirectCore Jungle Series includes lines ranging from weights 7 to 10 in a series of density options—from full floating to floating with a number of different integrated heads at varying sink rates. Retail is $119.99.