Ground penetrating radar (GPR) measurements are used for detailed imaging of limestone mound structures found in a limestone quarry in Scania, southwest Sweden. The reflected GPR signals offer a vertical resolution of about 0.5 m, and reflectors situated down to 10-15 m below the surface are detected. Marine seismic data collected in the offshore area between Sweden and Denmark image similar types of limestone. The seismic data offer a resolution that is more than an order of magnitude lower than the resolution of the GPR data, but they offer much larger depth penetration. The appearances of the characteristic limestone mound structures in the two different data sets are compared. The investigated limestone is a common rock type in the upper part of the sub-surface of eastern Denmark and southwest Sweden, and limestone deposits of similar age constitute oil and gas reservoirs in the North Sea. Detailed knowledge of the internal mound structures in the limestone is essential for evaluating the reservoir characteristics and potential of the limestone as well as for understanding the geological evolution of the mounds.