A new method for determining the bulk density of uncompacted surficial peat from field settings is presented. Most importantly, a new peat sampler was developed to ensure minimum disturbance of the peat sample. The main benefits of the new device are (1) from the moment of field sampling, the peat sample remains undisturbed in an inner collecting liner, which has a fixed volume and fits perfectly in an outer cutting tube, until the sample is ready to be analyzed in a laboratory, (2) the risk of fracturing or disturbing the sample during lifting it to the surface is significantly reduced by using a vacuum pump or hose to reduce suction at the base of the peat core, and (3) the razor-sharp cutting edge of the outer tube easily cuts through all kinds of fibers by short rotational movements. Furthermore, sufficiently large samples can be extracted, thereby accounting for the heterogeneous character of peat. The device is relatively light and easy to operate, which is a great advantage in the often remote and difficult-to-access peatlands. The sampler was successfully used during test trials on different types of fen peat in the Biebrza National Park, Poland.