Systematic rock mass characterization is an integral part of rock engineering practices. In the present scenario several classifications are in used for rock mass characterization for tunnelling. The present paper discusses engineering geological investigations carried out for Punasa tunnel, a part of Narmada Sagar project. The horse shoe shaped tunnel is 3675.25 m long and 9 m in diameter. This straight and free flow tunnel has been constructed in basaltic lava flows erupted during Cretaceous to Eocene age, belonging to poor to fair rock mass rating (RMR) and extremely poor to good in tunnel quality (Q-system). The values of RMR and Q-system ranges from 29 to 74 and 0.0825 to 13.33 respectively.