Understanding permafrost processes and changes requires long-term observational datasets. This dataset is a continuation of the dataset available from the long-term observational site Samoylov, located in the Lena River Delta, Siberia (72.37°N, 126.48°E). The location is characterized by a cold, dry tundra climate with mean annual air temperature of -11.7°C (using years with complete data between 1998 and 2017). The monthly mean temperatures over this period varied between 9.4°C in the warmest month (July) and -31.7°C in the coldest month (February). The average summer rainfall (June-October) was 145.2 mm. This dataset adds recent years to the observations of meteorological parameters, energy balance, and subsurface observations which have been recorded since 1998. The setup of the active layer monitoring grid (CALM) is explained in Boike et al. (2019). The data provide observations of active layer depth twice per month in summer at 150 points on a regular grid. In addition, the surface type of each point is provided (polygon center, rim high, rim flat, slope, and crack), representing landscape heterogeneity. The observations are suitable for use in integrating, calibrating and testing permafrost as a component in Earth System Models. The resulting quality-controlled dataset serves as a baseline for future studies.