It's all for "reference material" and research in their "upcoming open world games," and the captured sky is partially used in Mad Max. They mention Just Cause and how important water simulation is.
"Just Cause 2 is used as an illustration throughout," blurbs the dev diary description for 'Avalanche Studios in the Jungle'. It's no secret fans want more Just Cause.
"...but the reference material collected will prove useful in many of our upcoming open world games. In fact, some of the skies that we captured in Costa Rica will make it into Mad Max, which is currently in development at Avalanche Studios in Stockholm." The Avalanche team went to Costa Rica in early spring of this year.
"In the Just Cause games we're in a tropical paradise," says Andreas Oberg, associate art director.
"And one really important component of tropical paradises is beaches and water. However, water is one of the most complicated things to simulate in movies and computer games. So, yesterday, we were down at the beach and we were recording the water in super slow motion." Just Cause 2 was set in Southeast Asia on fictional Panau.
"These are all really interesting questions that we're doing research about so that we can improve things for the future."
Recently a community-built multiplayer mod for Just Cause 2 was.