We consider a system consisting of a set of mobile sensors. They are disseminated in a region of interest and their mobility is controlled (as opposed to mobility imposed by the entity on which they are embedded). A routing protocol in this context enables any point of the region to be reached starting from any node, regardless of the initial sensor deployment. This operation involves message forwarding and/or sensor motion. In this paper we present Grasp, a GReedy stAteless Routing Protocol for mobile wireless sensor networks (WSN). Grasp is simple and independent from the underlying communication model, but still provides results close to the optimal, with respect to the self-deployment of sensors over a given region. It ensures that (i) routing is always possible in a mobile WSN irrespective of the number of sensors, and (ii) above a given number of sensors in a considered zone the protocol eventually enables the routing to no longer require sensors to move, which yields to self-deployment. With Grasp, sensors autonomously reach a stable full coverage following geometrical patterns. This requires only 1.5 times the optimal number of sensors to cover a region. A theoretical analysis of convergence proves these properties. Simulation results matching the analysis are also presented.