Peat carbon (C) is one of the largest pools of soil C globally and is sensitive to environmental and climatic changes. Peatlands in the Kenai National Wildlife Refuge have been studied for their hydrology, vegetation composition and succession, peat accumulation, and similar characteristics, but their mass of stored C remains unknown. We use a synthesis of soil and wetland surveying techniques to generate estimates of C mass at two sites selected for suitable topography and hydrology. Manual probing of peat depth at 208 points across both sites provided calibration for radar velocity (medians 0.039 m·ns-1 and 0.037 m·ns-1) of a low-frequency (100 MHz) ground-penetrating radar (GPR), utilized to identify peat basal horizons. GPR surveys collected data points more efficiently than probing: >26,000 traces over 4.9 km of lines in half the time. We calculated total C mass from basin volume estimates via kriging interpolation surfaces with peat core C content and bulk density values, yielding estimates of 4,172 and 3,473 metric tons C (tC) for the two sites. Nearly equal site surface areas of 2.1 hectares yielded areal densities of 1,948 and 1,628 tC per hectare, respectively. Peat core analyses of C isotopes, organic matter content, nitrogen content, and 14C dating illustrate a similar Holocene history, but site conditions vary despite proximity. Variances in bulk density, vegetation abundance and diversity, and surface water presence are likely influenced by local topography, subsurface hydrologic connectivity, and the establishment history of peat-forming vegetation.