Abstract: Optomechanical devices enhance the interaction of light with matter by combining strong optical confinement with resonant mechanical motion. They have been shown to enable new science, such as the generation of macroscopic entanglement, have promising quantum technological applications, such as quantum memories and interfaces, and allow exquisitely precise measurements, such as the detection of gravitational waves from distant events in the universe. At nanoscale, they promise to provide the ability to observe and control complex phenomena that is otherwise inaccessible. In this talk, I will discuss two such applications within my laboratory. The first, biomolecular optomechanics, where the optomechanical interaction allows us to probe single-protein dynamics at speeds orders of magnitude faster than other technologies and to observe conformational dynamics for the first time without fluorescence. The second, superfluid helium hydrodynamics, where nanoscale optomechanical devices allow us to observe hydrodynamic phenomena such as coherent vortex dynamics, backwards wave breaking and soliton fission, that were predicted half a century ago but have not previously been seen. Broadly, I am to convince you that nanoscale optomechanics provides a powerful new tool that can be applied to drive new understanding across a wide range of fields.