This paper presents an innovative technology called 30 virtual colonoscopy, which incorporates several advanced visualization techniques to enable the physician to virtually examine the inner surface of the entire colon for identifying and inspecting colonic polyps. We first describe our unique process of acquiring and reconstructing a patient's colon model, followed by the novel visualization algorithms that we have developed to provide automatic planned navigations as well as interactive guided navigations inside the colon. Finally, we present our experimental results on a simulated pipe phantom, the Visible Human data set, and patient data.