The rates of chemical reactions (or any activated process) are by definition determined by the flux of reactants (or initial states) that end up as products (or final states). Through the last hundred years of studies on reaction rate theory, it has become clear that this can be equated to the flux through any surface that divides reactants from products as long as only those trajectories that end up as products are included in the flux. Transition state theory (TST) ignores this last clause. That is, it overestimates the rate if any of the trajectories recross the dividing surface. However, its advantage is that it replaces a dynamical calculation with a geometric one. Through a variational principle or perturbation theory, however, one can construct non-recrossing dividing surfaces that lead to exact rates [Chem. Phys. 370, 270-276 (2010)]. These approaches are limited by the nature of the search space of surfaces and the reference dividing surface, respectively. We will discuss recent approaches for determining such dividing surfaces geometrically using non-perturbative approaches [J. Chem. Phys. 155, 210901 (2021)]. Moreover, we can also address reactions under conditions far from equilibrium in so-called complex environments.