The benefits of immersive visualization are primarily anecdotal; there have been few controlled user studies that have attempted to quantify the added value of immersion for problems requiring the manipulation of virtual objects. This research quantifies the added value of immersion for a real-world industrial problem: oil well-path planning. An experiment was designed to compare human performance between an immersive virtual environment (IVE) and a desktop workstation. This work presents the results of sixteen participants who planned the paths of four oil wells. Each participant planned two well-paths on a desktop workstation with a stereoscopic display and two well-paths in a CAVE™-like IVE. Fifteen of the participants completed well-path editing tasks faster in the IVE than in the desktop environment. The increased speed was complimented by a statistically significant increase in correct solutions in the IVE. The results suggest that an IVE allows for faster and more accurate problem solving in a complex three-dimensional domain.