The structure and dynamics of biomolecules such as DNA and proteins determine the functions of underlying biological systems.  Modeling biomolecules is, however, extremely challenging due to their enormous complexity.  Recent years have seen the initial success of variational implicit-solvent models (VISM), implemented by the level-set method, for biomolecules.  Central in VISM is an effective free-energy functional of all possible solute-solvent interfaces, coupling together the solute surface energy, solute-solvent van der Waals interactions, and electrostatic contributions.  The level-set relaxation of such a functional determines numerically biomolecular equilibrium conformations and minimum free energies.  Comparisons with experiments and molecular dynamics simulations demonstrate that the level-set VISM can capture the hydrophobic hydration, dry-wet fluctuation, and many other important solvation properties.  This talk begins with a review of the level-set VISM and continues to present new developments around the VISM. Mathematical theory and numerical methods are discussed, and applications are presented.