In order to reduce the end to end packet delay and increase the packet delivery ratio in the Underwater Sensor Network(UWSN)

balancing the energy consume of nodes

and extending the network lifetime

a new Depth Based Directional Routing (DBDR) protocol based on the Depth Based Routing (DBR) was proposed. The new protocol sets up a virtual routing pipe with radius

and its axis is the line between the source node and target node. Only the nodes in the pipe are allowed to forward packets

and the nodes forward packets in the depth based routing protocol. Also

DBDR proposes a forward delay algorithm

sets the depth and rest energy as weight factors. In the comparison experiments with DBR on the NS2

the end to end packet delay of DBDR protocol decreased about 23%~42%

the packet delivery ratio reached to more than 95%. The results show that the protocol not only can better balance the energy consume of nodes and prolong the survival time of the whole network

but also achieve very high packet delivery ratios and much lower end to end delay.