This investigation set out to obtain data on the ecology, foraging and acoustic behavior of Chilean blue whales (Balaenoptera musculus) in the Gulf of Corcovado, which is an important feeding ground. We deployed 17 suction cup attached sound and orientation recording tags (DTAGs) on blue whales in 2014-16, for a total duration of 124h 08 min. Acoustic data on the tags revealed a variety of different calls. These included SEP2 (Southeast Pacific) song, previously described in this area, as well as other call types not previously described for Chilean blue whales. Downsweep calls similar to those described for other blue whale populations were observed on several tags, as were various other less stereotyped calls. We are currently working on characterizing these call types and also on using the accelerometers to identify calls from the tagged animal. Tag data will prove useful for interpretation of data collected in this area from passive acoustic monitors (PAM), both for species identification and possibly also density estimation. Overall, this work has the potential to greatly increase knowledge of the biology, ecology and behavior of blue whales in the Gulf of Corcovado.