We consider the continuous Anderson operator H = ∆ + ξ on a two dimensional closed Riemannian manifold S. We provide a short self-contained functional analysis construction of the operator as an unbounded operator on L 2 (S) and give almost sure spectral gap estimates under mild geometric assumptions on the Riemannian manifold. We prove a sharp Gaussian small time asymptotic for the heat kernel of H that leads amongst others to strong norm estimates for quasimodes. We introduce a new random field, called Anderson Gaussian free field, and prove that the law of its random partition function characterizes the law of the spectrum of H. We also give a simple and short construction of the polymer measure on path space and relate the Wick square of the Anderson Gaussian free field to the occupation measure of a Poisson process of loops of polymer paths. We further prove large deviation results for the polymer measure and its bridges. Contents c 1+ln(µ(M)/2) 1/α as a lower bound for the spectral radius. We also note that our method of proof gives gives the same conclusion as in Theorem 48 when working on a manifold equipped with a positive smooth density and its associated Laplace operator, or when working on a graph or a Dirichlet space.