Bolivia is a country with varying landscape. There are deep valleys, rainforests and high mountains. Bolivia consist partly of the mountain chain Andes. In the Andes there is a big plateau; Altiplano. On Altiplano is the world´s highest navigable lake, Lake Titicaca. It lies on an altitude of approximately 3800 meter above sea level. The lake covers an area of 8300 km2. In 1999 the Terra satellite was sent up. Onboard is the MODIS instrument. It views the entire earth´s surface every 1-2 day. MODIS is acquiring data in 36 spectral bands, and its data will improve our understanding of global dynamics and processes occurring on the land, in the oceans and in the lower atmosphere. This big area of open water is perfect for in-situ measurement for calibration of the satellite. In-situ measurements were made on Lake Titicaca in May and June 2000. Floatingsystems were placed in the lake to cover an pixel (for MODIS). The measurements showed good agreement in bands 20-23, 29 and 31-32. There were some difficulties with the measurements in field because the local population was not aware of our experiments and altered our equipment.