Network lifetime is often a crucial measure of the cost-effectiveness of underwater wireless sensor networks and a guiding factor of their deployment. In this paper, we propose a placement strategy for surface gateway nodes in order to maximize network lifetime under a given set of functional requirements. We formulate the problem as an optimization problem and solve it for sample networks. Results show a trade-off between lifetime and other performance metrics, such as average end-to-end delay. We propose a multi-objective reformulation of the problem to strike the required balance between performance and lifetime.