Visualization of the cool gas distribution around the third most massive halo in TNG-Cluster at z = 0. The field of view is 3R_200c from side to side, as well as in the projection direction, which is random with respect to the cluster itself. The large white circle shows the ∼2 Mpc virial radius of the cluster itself. Color indicates neutral hydrogen column density, a tracer of cool ∼10⁴ K gas. While tracer amounts of cool gas pervade the cluster environment (blue), the vast majority of cool gas mass is at higher column densities (green and orange). This material is predominantly localized in and around satellite subhalos, where the most massive 100 such subhalos are enclosed with white circles, with radii equal to their half mass radii.