At RMIT University in Melbourne, a team of engineers has answered a question that has quietly frustrated materials science for decades: can a metal structure be made light enough, and resilient enough, to float? By filling 3D-printed titanium lattices with polyurethane foam and rethinking how density itself is measured, researchers have produced a material stronger than steel that refuses to sink — even when broken. The discovery arrives at a moment when the world's marine infrastructure is aging, and the sea is asking harder questions of the materials we trust to hold things together.