In this paper, we consider MAC (media access control) protocols appropriate to the underwater acoustic networks. First, we consider a media access method based on the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol used in the wireless local area networks IEEE 802.11 (WiFi). In the underwater acoustic channel, the acoustic wave propagates very slowly with regard to the electromagnetic wave (about 1500 m s ). Therefore the propagation delay is significant and thus collisions present a high cost considering the delay of transmission and the available throughput. To avoid this problem, we consider a second protocol in which we integrate a WAIT command [1]. Finally we integrate to our proposition a power control mechanism in order to increase network performance (delay, throughput). The performance evaluation of the three propositions has been done in terms of available throughput of the underwater sensors, delay of transmission and collision probability. The proposed simulation system model is detailed.