Abstract:This paper provides an overview of how and why acoustic waves are important for underwater communication when compared with radio and optical waves, underwater acoustic channel, it's characteristics and model. Also about the underwater sensor architecture, challenges faced by sensor nodes in the network and Media Acess Control(MAC) protocol solutions for them. This paper also describes about the various communication approaches including channel coding in underwater and their performance analysis for different approaches used. Through these approaches, multiple underwater vehicles can communicate among themselves as well as with the console with minimal Bit Error Rate.