A symposia was held to discuss tunneling in hard rock, deep below ground surfaces. The goals were to: describe tunneling experiences in Chicago, western United States, Canada, and Europe; discuss some of the multiple-use aspects of deep tunnels; assess the future of rapid excavation in hard rock using mining machines; and encourage those facing combined sewer and flooding problems to assess the potential use of tunnels. The flooding and combined-sewer overflow problem is discussed, as are the investigations and plans of the Metropolitan Sanitary District of Greater Chicago for constructing a deep tunnel system to alleviate flooding and pollution from combined-sewer overflows. The potential of pumped-storage hydroelectric power generation and circulation of condenser water from underground nuclear generating plants, in conjunction with tunnel construction, is treated. Experiences with mechanical moles in the United States and other countries in boring through hard rock are described. Suggestions are given concerning pre-construction investigations, planning and design that can minimize field problems, expedite tunneling procedures, and reduce tunneling costs. Various viewpoints are presented.