When you start using one, you will realize that there are huge areas of lakes that have few or no fish in them. No sense fishing where they aren't. I realize that fish go into and out of areas, but it's still nice to know wether they're in the area or not. I agree that the most important use is to pinpoint structure, but trout & kokanee, for instance, along w/wipers are less prone to hang on structure and more into cruising-just like a bunch of teenagers on Saturday night. Once you start using a sonar, you'll wonder why you waited so long to get one!