By installing fog catchers in the hills around Lima, Peru, conservationists seek to transform fog into water for use in infrastructures of fog oasis reforestation. This article describes the devices and techniques of inquiry through which fog was gradually rendered catchable. These relational engagements with the atmosphere, and the multifarious forms that fog assumed along the way, will be used to reflect on the possibilities and limitations of speculative realism for more-than-human ethnography. Particularly relevant is Graham Harman's notion of ‘vicarious causation’, which denotes how things located outside thought can be accessed vicariously and partially, for example, through allusion. My contention is that this concept may be productively adapted for ethnographic inquiry if repurposed to fit with an open-ended and relational understanding of the outside.