In this talk I will discuss efforts to numerically model various physical processes in lakes. One aspect of the talk will consider internal wave motions on the basin scale, while the other will consider smaller scale modelling involving the interaction of internal waves with the lake bottom. In each case the typical, publicly available numerical model is under-resolved or somehow misrepresents the physics that occurs in the field. Sometimes, this is by design, with convenient mathematical approximations (e.g. the hydrostatic approximation) and properties of numerical schemes (dissipation) resulting from the a priori decision to under-resolve the physical processes in question. At other times this is by necessity, since the physical phenomenon in question spans too many scales to be adequately resolved. I will discuss efforts to circumvent under-resolution with either improved physical parametrizations (e.g. weakly non hydrostatic effects), improved numerical methods (high order discontinuous Galerkin methods), or high resolution 'scale-up' numerical experiments using direct numerical simulations.