The hard problem generates a crowded field of competing philosophical positions, each offering a different diagnosis of what consciousness is and where it fits in a physical world.
Substance dualism (Descartes): mind and body are fundamentally different substances, thinking stuff (res cogitans) and extended stuff (res extensa). This explains the explanatory gap: of course experience isn't reducible to physics, because it isn't physical. The problem: how do two completely different kinds of substance interact? How does your decision to raise your arm, an event in the non-physical mind, cause your arm to actually rise, an event in the physical world? Every version of interaction dualism faces this causal interface problem, and no one has solved it.
Property dualism: there is only one substance (physical), but mental properties are distinct from and not reducible to physical properties. Your brain is a physical object, but it has both physical properties (mass, temperature, neural firing rates) and mental properties (the feel of your current experience) that are genuinely distinct. Chalmers is a property dualist. The advantage: avoids the interaction problem. The problem: if mental properties are causally inert (they aren't physical, so they can't do physical work), how do they influence behavior? This is the problem of epiphenomenalism.
Physicalism / identity theory: mental states are identical to brain states. Pain just is a certain pattern of neural activity, not caused by it, not accompanied by it, but identical with it. The advantage: no mysterious non-physical entities. The problem: the multiple realizability objection. If pain in a human is one pattern of neural activity and pain in an octopus (with a completely different nervous system) is a completely different pattern of neural activity, then "pain" can't simply be identical to any one physical state, the same mental state type can be realized in multiple different physical substrates.
Functionalism (Putnam, Fodor): mental states are defined by their functional roles, their causal relations to inputs, outputs, and other mental states, not by their physical substrate. Pain is whatever state is typically caused by tissue damage, causes distress and withdrawal behavior, and interacts with beliefs and desires in certain ways. This allows for multiple realizability and for the possibility of artificial minds. The problem: the Chinese Room (Searle) and zombie arguments suggest that functional organization might be present without any accompanying experience.
Eliminative materialism (Churchland): our ordinary concepts of mind, belief, desire, sensation, experience, are part of a radically defective folk psychological theory that will be entirely replaced by mature neuroscience. We don't need to explain experience; we need to eliminate the concept and replace it with properly neuroscientific ones. The courage of this position is admirable. The problem: the claim seems self-undermining. Paul Churchland doesn't believe in beliefs? He has no experiences? When eliminativists deny the existence of conscious experience, they are performing an act that seems to require conscious experience.
Panpsychism: consciousness is a fundamental feature of reality, present in some form everywhere, not just in brains but in all physical systems, at varying levels of complexity and integration. This is Whitehead's view, and it is having an unlikely renaissance in contemporary philosophy of mind as a response to Chalmers' hard problem. The advantage: if experience is fundamental and ubiquitous, we don't need to explain how it arises from non-experiential matter. The problem: the combination problem, how do the micro-experiences of individual particles or neurons combine to produce the unified, rich experience of a person? Solving the combination problem seems as hard as the original hard problem.