Abstract: This paper presents a reliable and robust low data rate spread spectrum approach which is implemented in the acoustic underwater communication system for shallow coastal waters. It shows operation assumptions of spread spectrum techniques based on the well- known Shannon equation. It describes two methods of spread spectrum: frequency hopping spread spectrum and direct sequence spread spectrum; their block diagram and their characteristics are then listed to make comparisons. In short, adverse channel effect is analyzed on the expected operation of the system. I present the platform for the target implementation of the acoustic underwater communication system, which now has to allow continuous and easy development of stable algorithms.