Wireless Sensor Network: Survey
Underground Sensor Network: Survey
Routing Protocol for Underwater Sensor Networks:
This is a good research problem to work on. You can read papers from scholar.google.com.
You have to know basic of Underwater Sensor Networks(UWSN)
Read this two paper first:
"Underwater acoustic sensor networks: research challenges" http://www.sciencedirect.com/science/article/pii/S1570870505000168
"State-of-the-art in protocol research for underwater acoustic sensor networks" http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.212.4574&rep=rep1&type=pdf
Then read papers on routing protocol in UWSN (Here are two famous routing protocol for UWSN):
VBF: vector-based forwarding protocol for underwater sensor networks, http://engr.uconn.edu/~jcui/UWSN_papers/UCONN_CSE_UbiNet-TR05-03.pdf
DBR: depth-based routing for underwater sensor networks, http://saluc.engr.uconn.edu/publications/yan08dbr.pdf