According to Law number 23 year 2014 about Regional Government, districts/regency have full authority to manage its territory. This Law makes boundary become an important thing. Rule about determination and affirmation of district boundaries both land and sea have been regulated in Permendagri number 76 year 2012, including regulate the base map that used to determine the maritime boundary. Determination boundary within district/regency coverage, base map used is the LPI Map. However, not all regions in Indonesia have LPI Map, so it's important to do research in order to know the base map that can be used for the determination of maritime boundary as an alternative of LPI Map.The base maps to be processed and analyzed in this study are RBI map, Landsat 8 satellite images, and LPI map. Processing use cartometric method, and drawing boundary between Sumenep and Pamekasan regency using equidistant line. The base line used is the normal base line, straight base line, and bay closing line. Processing use arcGIS software, autocad, and ENVI. From the results of processing, obtained coordinates of boundary point and dimension of maritime boundary. The area in this study is divided into three areas to simplify the calculation of area. However on the LPI map there are only two areas because in the third area (Masalembu Islands) has not been mapped. Dimension of maritime boundary of satellite image overall 666.125,240 Ha with details of area I 332.218,013 Ha; area II 253.719,973 Ha; and area III 80.187,254 Ha. On the map of RBI as a whole 759.487,316 Ha with details of area I 333.848,076 Ha; area II 345.730,540 Ha; and area III 79.908,700 Ha. While on the LPI map in overall 608.340,895 Ha with details of area I 333.958,828 Ha and area II of 274.382,067 Ha.