Researchers have worked on routing issues for adhoc-networks, VANET’s, and Wireless Sensor Networks in a normal scenario; recently there has been a recent trend towards the study on underground wireless networks and proposals for design and development for Wireless Underground Sensor Networks. This paper highlights the concept of wireless underground sensor network in the coal mine environment, its application and various protocols related to underground coal mine environment have been studied. The focus is on various issues, routing protocols and parameters used for comparison of their performance with an insight into the applications of underground wireless sensor network. No doubt, the WUSN has its own share of challenges and the research has just started.