This comprehensive guide explores the complexities and innovations involved in designing and planning underground mining projects. With surface resources declining and environmental standards tightening, underground mining is becoming the preferred method—expected to surpass 55% of global production by 2025. Key themes include: Fundamentals of Underground Mining: Emphasizes tailored designs for each deposit, with a focus on maximizing mineral recovery and minimizing waste and environmental impact. Modern Design Principles: Moves away from rigid, deterministic models to flexible, scenario-based planning using advanced 3D tools and sensitivity analysis, improving efficiency and profitability. Challenges and Opportunities: Covers critical issues like geomechanical stability, access design, ventilation, dilution, and recovery. It highlights the growing role of backfilling and real-time data in managing risks and improving sustainability. Software Integration: Critiques the fragmented nature of current tools and calls for fully integrated systems to support smarter decision-making and streamline operations. Method Selection and Optimization: Offers frameworks (like the Nicholas and UBC methods) for choosing mining methods and optimizing stope design, production schedules, and infrastructure. Access and Infrastructure: Details criteria for shafts, ramps, and galleries, and their role in supporting safe, efficient, and flexible mine development. Sustainability and Closure: Emphasizes the need for early planning of mine closure, using proven technologies and designs that support long-term environmental and economic sustainability. Overall, the document promotes a forward-thinking approach to underground mine design, combining technical rigor with strategic adaptability.