Time reversal (TR) is a technique that utilizes spatial diversity to achieve spatial and temporal focusing in complex environments. This approach has been successfully applied to phase-coherent acoustic communications in time-varying multipath environments, providing an alternative to conventional adaptive multichannel equalizers (M-DFE). Essentially, the TR method involves combining multichannels as a spatial precombiner, effectively reducing channel complexities and achieving optimal performance. This presentation will discuss the insights gained from using the TR approach for underwater communications under diverse underwater conditions.