Exploration　of　advanced　technologies　employed　for　streamlining　UWSN　devices　is　a　hot　issue.　Challenges　faced　by　UWSN　are　high　power　consumption,　increased　propagation　latency　and　dynamic　topology　of　nodes.　Depth-based　routing　protocols　are　designed　to　cope　these　challenges　that　use　depth　information　to　forward　data　toward　surface　sink.　Depth-based　routing　and　energy　efficient　depth-based　routing　are　widely　used　routing　protocols　in　UWSN.　DBR　has　low　stability　period　due　to　un-necessary　data　forwarding　and　high　load　on　mid　and　low-depth　nodes.　In　DBR　quick　energy　consumption　of　nodes　creates　large　holes　in　the　network.　The　path　connectivity　hole　leads　retransmission　of　packets　that　consumes　excessive　energy,　route-update　cost　and　end-to-end　delay.　In　this　paper,　the　proposed　robust　depth-based　routing　protocol　is　used　to　overcome　deficiencies　of　DBR　by　limiting　number　of　forwarding　nodes　considering　variation　in　depth-threshold,　holding-time　and　distance-differences　to　minimise　end-to-end　delay.　Copyright　©　2020　Inderscience　Enterprises　Ltd.