We study the equilibrium structure and dynamics of unconcatenated unknotted polymer rings in the melt. In accordance with earlier studies we find that rings in the melt are more compact than linear chains. We show that rings interpenetrate less and, perhaps as a result, diffuse faster than linear chains. Ring diffusion is faster for all ring sizes studied, the largest ring having numbers of monomers approximately ten times greater than the entanglement crossover of linear chains.