Maritime activities are among the most significant sources of noise pollution in the marine environment. Many attempts to map ocean noise propagation and support environmental impact assessments have taken place around the globe, either through field measurements or, recently, through mathematical and computational modeling. In this context, Santos Basin, the most crucial oil province of Brazil and marked by a growing offshore activity, has been the object of an extensive underwater acoustic monitoring project (PMPAS-BS), a pioneering initiative under the environmental licensing of oil and gas Production fields in Santos Basin. This work presents the underwater acoustic modeling framework developed in this project and its first results. The noise radiated by anthropogenic (ships and platforms) and environmental sources (waves and winds), in the particular 1/3 octave bands of 63 Hz and 125 Hz, were computed with the use of a normal modes model to generate monthly and annual Sound Pressure Level (SPL) maps with resolution of 1/6 degree. Results obtained so far reveals good agreement between model and observed data, especially on regions of higher AIS coverage. The values are on the order of the measurement accuracy and qualifies the modeling approach as an essential tool for underwater noise characterization.