Surrounded by extensive lake waters, Samosir Regency has beach tourism potential that can attract foreign and local tourists. However, the water level of Lake Toba has decreased in recent years, allegedly due to changes in land cover around the Sidikalang and Samosir groundwater basins, which impact shoreline changes. This change in coastline will affect the function of the beach as a tourist destination if we do not have a good planning strategy. The purpose of this research is to identify changes of the coastline occurred in 1995, 2008, 2017. Then look at the factors that influence change, and determine what form of tourism is appropriate to deal with this change in coastline. The method used is remote sensing and geographic information systems (GIS) combined with the shoreline change method, namely DSAS (Digital Shoreline Analysis System). The results of the study found that the average rate of change of shoreline in Samosir Regency experienced an acretion of 1.3 meters/year and a abration of -0.3 meters/year. Changes in shoreline generally occur in areas that have a slope of 0 -2%. Changes in land cover around CAT Sidikalang and Samosir on Landsat imagery in 1995 and 2017, there was a decrease in primary forest land cover area by 468.4 km 2 and secondary forest by 447.6 km 2 , which would undoubtedly have an impact on reducing the rainwater catchment area in the region.