The primary objective of this research is to examine the difficulties encountered in underwater acoustic Sensor Networks (UASN) due to empty spaces in acoustic route routing. The presence of empty areas inside the network often results in the unsuccessful transmission of data packets in sparsely populated underwater acoustic sensor networks (UASNs). The current techniques used to identify and circumvent empty spaces are characterized by a significant expenditure of time and a reliance on location data. To tackle this issue, the study introduces a new protocol named Secure Opportunistic Vacant Hole Avoidance Routing (SOVHAR), which aims to enhance routing pathways by disregarding vacant spaces. The proposed approach guarantees the continuous transmission of packets to the intended destination by using a local neighbourhood search strategy on sensor nodes. This strategy considers several criteria, such as node depth, signal amplitude, and the number of intermediate hops. The protocol further considers variables such as salinity, losses, and noise level to enhance the precision of the localized search for energy-efficient packet transmission. A fitness function is established to assess the efficacy of a sensor node in transmitting data packets, therefore aiding in avoiding areas with limited coverage while minimizing additional costs. The efficacy of the proposed SOVHAR is assessed via simulations, demonstrating its energy efficiency and capability to avoid empty spaces while considering different communication factors. This evaluation highlights its enhanced resilience compared to current methodologies.