An acoustic local area network has been deployed for multipoint-to- point telemetry between ocean bottom sensors and a surface receiver in deep- water areas. A major obstacle for coherent communications in this channel is strong multiple-access interference from other acoustic modems, which affects a common narrowband request channel of the network protocol. The network throughput and packet delay depend on the capability of the receiver to resolve collisions between request packets. In this paper a multiuser receiver for joint channel parameter estimation, multiple-access interference suppression and signal detection is proposed. The receiver is fully adaptive, requiring no side information about the channel conditions or the signal parameters of the interfering users in the network. Receiver performance is demonstrated through experiments in a deep-water acoustic channel.