Apparatus and method including cell primitive for unstructured volume rendering. For example, one embodiment of an apparatus comprises: a ray generator to generate a plurality of rays in a first graphics scene; a hierarchical acceleration data structure generator to construct a hierarchical acceleration data structure comprising a plurality of hierarchically arranged nodes including leaf nodes and inner nodes; traversal circuitry to traverse one or more of the rays through the hierarchical acceleration data structure; unstructured volume intersection circuitry to intersect a ray with an unstructured volume primitive within a leaf node of the hierarchical acceleration data structure, the unstructured volume intersection circuitry to determine multiple intersection hits between a ray and an unstructured volume primitive.