This dataset describes six sediment cores (12 - 219 cm length) from different landscape features in a coastal permafrost thermokarst affected landscape in the Theshekpuk Lake region in Arctic Alaska. They are located in a transect from inland to coast, to describes the transitional dynamics between terrestrial and marine permafrost and thermokarst. The cores were drilled during the Perma-X Lagoon expedition in April 2022. The three unfrozen cores from a marine (MAR, 12 cm length), an intact lagoon (LAG, 31 cm length) and a thermokarst lake (TKL, 50 cm length) site, were all sampled using a Push Corer. The three frozen cores, including upland permafrost (UPL, 203 cm length), drained thermokarst lake basin (DLB, 219 cm length) and semi-drained lagoon (SDLAG, 183 cm length) deposits, were drilled using a SIPRE Corer. The hydrochemical analysis included the uppermost samples of each core and in case of the frozen cores additionally samples from the middle and the bottom sections of the cores. Measured parameters were pH values, electrical conductivity (EC) [mS/cm], and dissolved organic carbon (DOC) [mg/L].