The purpose of this paper is to present the results obtained from field spectroscopy campaigns for detecting underground structures. Simple Ratio (SR) Vegetation Index, was utilized for the development of a Vegetation Index-based procedure aiming at the detection of underground military. The measurements were taken at the following test areas such as: Area (a) vegetation area covered with the vegetation (barley), in the presence of an underground military structure and Area (b) vegetation area covered with the vegetation (barley), in the absence of an underground military structure. The results show that the SR Vegetation Index is highly useful in detecting deep man-made infrastructures in Cyprus.