University College London's Extreme Citizen Science research group (UCL ExCiteS) is experimenting with ways to incorporate the most marginalized communities into participatory citizen science activities through which they can share their indigenous knowledge. The group works with communities at the extremes of the globalized world--both because of nonliteracy and the remote or forbidding environments they inhabit. These groups are the gatekeepers of some key environments on which the future health of the planet depend--from tropical forests to Arctic sea-ice. This article presents the methodologies and tools the group is developing to give these people a voice. This article is part of a special issue on pervasive analytics and citizen science.