A geographic information system (GIS) is a computer-based information system using special tools to manage location-based data and their attributes for decision-making. Geospatial functions cut across many fields and support problem solving through geodata design and analysis. GIS have been used, for example, in environmental conservation and wildlife management. Its use in tourism planning, development and management, and marketing of destination products is only a more recent approach. The adoption of the technology affects both the sustainability of environmental resources and the quality of tourists' experience. The purpose of this chapter is, first, to explore the functionalities and usage potentials of GIS in the tourism domain. Second, two studies of Maasai Mara Game Reserve and Nairobi National Park portray how GIS and satellite remote sensing imagery is applied to assess the ecosystem's changes, their causes, and major implications. Examination of Landsat satellite image data for 2000 and 2017 shows that due to conversion of areas to farmlands and settlements, the coverage of Mau Forest Complex, the main catchment area for the Mara ecosystem, had reduced by 30.2% and vegetation by 22.8%. The analysis of Nairobi National Park showed that the Kitengela wildlife migration corridor has been completely encroached by human settlement and mining activities, thus seriously compromising the performance of the ecosystem. Mapping of human development pressure on the ecosystem using GIS technologies can be used to assess and manage the tourism resources potential in conjunction to biodiversity conservation as a critical element in improving wildlife as a tourism destination product.