This research concerns the development of an adaptive receiver for underwater communication. In this type of wireless link, the radio channel is replaced by an underwater acoustic channel, which is strongly dependent on the physical properties of the ocean medium and its boundaries, the link geometry and the ambient noise. Traditional acoustic communications have involved a priori matching of the signaling parameters to the expected characteristics of the channel. To achieve more robust communications, as well as high quality of service, it is necessary to develop a type of adaptive receiver for the acoustic link. This process involves estimating the channel scattering function by processing the received Direct Sequence Spread Spectrum (DSSS) acoustic signal. This information is used by an innovative receiver introduced for usage in the underwater environment. The research also involves the development of a robust acquisition system for the acoustic communication signal. The major design goal is the receiver's robustness on a Doppler distorted fast varying multipath fading channel, for applications in multiuser environments. Another important design goal is low complexity in signal processing. The proposed receiver is able to adapt in the acoustic channel variations. Experimental results prove the effectiveness of the receiver.