In May, 2003, fifteen sample stations were collected in Gulf of San Miguel, province of Darien, in order to determine different physical and chemical parameters such as: temperature, salinity, oxigen, pH, water transparency, sediment granulomery, and organic matter. The temperature recorded had a mean of 26.9 º C, ranging between 26.0 ºC and 29.0 ºC in all seasons. Salinity presented few variations with an average of 28.9 o/oo, with decreases in the converging area of Savana and Tuira rivers. Dissolved oxygen increased as the sampling stations move away from mangrove areas, while the range of pH was within the expected ranges. Water transparency was generally less than one meter, due to discharges from the Tuira-Chucunaque watershed, reflecting a silt loam consistency from most of the mud and clay sediment particles. The organic matter averaged 47% at the stations, with greater values in stations that were closer to mangrooves. Multivariate analysis indicates two well defined groups while physical and chemical parameters are more related with mud clay particles, temperature, salinity and transparency.