90% of what a trout eats is UNDER water. Not dry flies. Because of this strike indicator nymphing rules the underwater world of fly fishing. While other techniques like streamers or tight-line nymphing, no indicator, are effective they aren't even a close rival to the general population of indicator anglers. It's not easy to master, but it is very easy to understand. Your strike indicator acts as a float or bobber, telling you approximately where your nymphs are at and how they are drifting. Most anglers like to have their strike indicator about 1.5x the depth of the water. In 5' of water, position your indicator at about 7.5'. This is a general rule, and on the deep end of the spectrum in our opinion but it works. Very well. Anglers typically use weighted nymphs, fluorcarbon style tippet in the 3X-5X range, and an indicator. There is lots of specialized tackle. Give it a try!