Chalmers famously identified pinpointing an explanation for our subjective experience as the hard problem of consciousness. He argued that subjective experience constitutes a hard problem in the sense that its explanation will ultimately require new physical laws or principles. Here, we propose a corresponding hard problem of life as the problem of how `information can affect the world. In this essay we motivate both why the problem of information as a causal agent is central to explaining life, and why it is hard - that is, why we suspect that a full resolution of the hard problem of life will, similar to as has been proposed for the hard problem of consciousness, ultimately not be reducible to known physical principles.