In order to develop new research areas and methodologies to apply in the volcanic monitoring effort ongoing in the Azores archipelago, a preliminary survey was made in order to identify anomalous degassing areas in the Furnas lake. Degassing phenomena occur in several areas of the Azores archipelago in the form of fumarolic fields, thermal springs or carbonic mineral water springs. Nevertheless, diffuse degassing through soils, or through lakes also occur and the detection is possible only with gas detectors. Furnas lake was selected as a first test site for degassing in lakes in the Azores archipelago; thus 1537 measurements were made according a regular grid. Results show that CO2 flux in Furnas lake range between 0 g m-2 d-1 and values higher than 30000 g m-2 d-1. From the overall CO2 degassing measured in the Furnas Volcano area, 5% is emitted from the lake (59 t d-1), corresponding to ∼ 31 t km-2 d-1. This value reveals that Furnas lake corresponds to an important volcanic degassing area when compared to other lakes spread in volcanic systems worldwide.