Snezhnika and Banski Suhodol glacierets in the Pirin Mountains are the southernmost surface ice accumulations in Europe. Apart from direct snowfall, substantial inputs from avalanching feed both glacierets. Both glacierets appear to be more stable than any other small glacier in the Mediterranean region. Although accurate knowledge of ice thickness distribution and bedrock topography is essential to understand the long-term dynamics of these ice bodies, such data are lacking for the Balkan Peninsula glaciers. Detailed GPR measurements conducted in 2018 using a 100 MHz frequency antenna revealed a maximum thickness of 17 m at Banski Suhodol and 12 m at Snezhnika. Two distinct main layers revealed by density variations were inferred at Snezhnika and several clear internal reflections observed on the radargrams were associated with thin debris layers. Based on the morphological evidence of the former ice extents and high-resolution digital elevation models, 3D reconstructions of ice thickness distribution during the Little Ice Age (LIA) were generated. The results revealed that since LIA the volume of Snezhnika dropped by 123%, and that of Banski Suhodol by 83%. Both glacierets reached maximum thickness values 5 m greater than the present ones during LIA. For the first time, ERT measurements and miniature thermistors were used to investigate ground ice occurrence in the vicinity of the Pirin's glacierets. The ERT measurements revealed no glacial ice in the proglacial area of Banski Suhodol nor in the frontal moraine. Ice-rich frozen debris and frozen sediments without massive ice occur downslope the glacieret on a slope covered by loose rock deposits. Based on the ground surface thermal data, permafrost appears likely on this scree slope, where persistent or late lying snow cover occurs regularly. Our investigation revealed that permafrost is not necessarily related to rock glaciers occurrence in the Balkan Peninsula.