It has become common to diagnose that artificial intelligence (AI) leads to situations of "essential" epistemic opacity: situations that cannot be remedied by providing an epistemic agent with more or better information about the relevant process. A common but mostly implicit assumption in these debates is that epistemic opacity may be essential due to the nature of the processes themselves, rather than the epistemic situation of the agent. To clarify the possible meanings of essential opacity, I reverse the analytical perspective by asking what it would mean for a process to be essentially transparent. My conceptual approach navigates the distinct yet related meanings of "transparency" within various philosophical subdisciplines: transparency of mathematical models in the philosophy of science; transparency of content in the internalist and externalist variants of the philosophy of mind and language; and informational transparency of environments in the philosophy of biology. Based on a comparative discussion of these views, I argue that even the most a-prioristic philosophical accounts of content transparency render essential transparency at most a conceptual possibility. Thus, an asymmetry remains between this notion of transparency and the factual possibility of agent-independent opacity, which marks the boundaries of what can in principle be known by any finite agent. I conclude that, in virtually all real-world situations, situated and agent-centred accounts of transparent versus opaque processes are more meaningful.