What role did the Islamicate occult sciences play in the formation and transmission of environmental knowledge between Oman and East Africa? After the retreat of the Portuguese empire by the mid-17th century from Eastern Arabia and the Swahili Coast, Omani planters and peasants increasingly migrated to East Africa. They joined relatives or made new homes in the Omani transoceanic expanding agrarian economy. This movement across thousands of miles to the southern hemisphere enabled new opportunities for learning. Coming from a mostly arid ecology, the transoceanic crossings of these actors introduced them to alien flora and fauna in the newly encountered East African monsoon-rain fed forests and farmlands. Since the early modern period, the ensuing environmental conceptualizations, experiences, and affective interactions resulted in transporting not only environmental infrastructures but also a novel epistemology. It intertwined both Omani and Swahili occult sciences planted in the soil of East Africa. Several Omani jurists and polymaths have observed and learned from their environments, producing textual instruments in the form of grimoires, manuals, and treatises. These instruments employed not only Omani epistemic technologies but also locally rooted Swahili idioms and experiential ways of knowing. This transcultural convergence nourished the emergence of an epistemic field that represents a generative archive for environmental history. It takes into perspective the local and the translocal cosmological concepts and material praxis. In this paper, I draw on a variety of texts by Omani occultists from the 18th to the 19th centuries, and I read connected amulets, talismans, and other textual sites as a collective knowledge repository. Further, I trace how the occult practitioners aimed to enact ontological and material changes in the natural world. Building on the anthropologist Elizabeth Povinelli’s concept of “geontology,” I examine, among other fields, the environmental meaning of the occult in which non-life “geos” and being “ontology” come together. They inform the ways in which hydrological, ethnobotanical, and agricultural knowledge operated and circulated between the Arabian and African coasts; animated in occultist idioms written in both Arabic and Swahili languages. Moreover, I detail the process by which multilingual occultist works were theorized and phenomenologically experienced by literate and illiterate Swahili and Arab actors. This paper explores uncharted waters to write a connected environmental history told through a fusionist epistemological domain. Thus, it historically contextualizes the intersection between occult sciences and ecosystems in the environmental history of the Indian Ocean world.