When studying Laplace eigenfunctions on compact manifolds, their localisation or delocalisation properties at large eigenvalues are strongly related to the dynamics of the geodesic flow. In this talk, I will be interested in delocalisation phenomena, through the study of L∞ norms of eigenfunctions, on manifolds of negative curvature. After recalling the existing results and conjectures, I will show how these results can be improved by adding small random perturbations to the Laplacian. I will also present some deterministic improvements, in the case of manifolds of constant curvature. These are joint works with Martin Vogel, and with Yann Chaubet.