The DROPS Package for Numerical Simulations of Incompressible Flows Using Parallel Adaptive Multigrid Techniques. Characteristic Features: Discretization on tetrahedral grids using finite elements; Local grid refinement techniques; Level set methods for interface capturing; Continuum surface force approach for the treatment of the surface tension; Approximation of interface curvature using a weak formulation of Laplace-Beltrami-Operator; Efficient iterative solvers based on multigrid methods.