Abstract: Disclosed are hierarchical buoyant materials comprising porous components having multiple length scales that provide reduced density, higher strength, and improved buoyancy. The hierarchical buoyant materials include components having at least two length scales including a first porous material having elements characterized by a first linear length scale and a second porous material having elements characterized by a second linear length scale. The first porous material includes hollow microspheres, and the second porous material provides low effective density via geometrical arrangements. The second linear length scale is substantially different than the first linear length scale in terms of size, e.g., diameter, length, or distance.