Nazareth, P.Chandavarkar, B.R.2026-02-082021Lecture Notes on Data Engineering and Communications Technologies, 2021, Vol.53, , p. 747-76023674512https://doi.org/10.1021/acs.jpcc.5c04013https://idr.nitk.ac.in/handle/123456789/33766Underwater Acoustic Sensor Networks (UASNs) is a technology used in several marine applications like environment prediction, defense applications, and discovering mineral resources. UASNs has several challenges like high bit error rate, high latency, low bandwidth, and void-node problem during routing. In the context of routing protocols for underwater communication networks, the void-node problem is one of the major challenging issues. The void-node problem arises in the underwater communication during the greedy-forwarding technique, due to which packet will not be forwarded further toward the sink. In this review paper, we analyze the void-node problem in underwater networks and issues related to the void-node. Also, we elaborate on the significant classification of void-handling routing protocols. We analyze both location-based and pressure-based void-handling routing protocols. © Springer Nature Singapore Pte Ltd 2021.Routing protocolsUnderwater communicationVoid-node