<p>An underwater wireless sensor network (UWSN) is a promising technology for marine surveillance. To ensure the proper functioning of a UWSN and the extraction of accurate data, it is essential to include robust safeguarding and protection methods. Malicious node assaults have gained prominence and represent the most formidable attacks on UWSN. Numerous studies have been carried out to safeguard UWSN against malevolent assaults. The lack of a pre-existing security infrastructure is a problem and barrier for UWSN, since it has to identify and counteract unwanted assaults. This paper attempts to bridge some of these leftover gaps in the reported works. This paper proposes a novel algorithm, namely the Intelligent Intrusion Detection Model, which is constructed with secure routing by adopting the Ant Colony Optimisation Algorithm, which is named as IntSec_ACO. This proposed Integrated Security Ant Colony Optimisation (IntSec_ACO) framework enhances underwater wireless sensor networks (UWSNs) by combining trust-based deceptive node detection, secure routing, and localization. Trust is computed through direct, indirect, and anomaly-based assessments, while security-aware ACO adapts routing decisions using trust, link reliability, and energy efficiency. Detected deceptive nodes are localized through ACO-based minimization of localization error. By integrating detection, routing, and localization in an iterative cycle, IntSec_ACO achieves robust security and improved network performance under hostile underwater environments. The proposed IntSec_ACO outperforms existing algorithms already suggested for a similar study in terms of PDR, delay, encryption time, decryption time, Throughput, and Computation cost. Performance Comparison analysis of the proposed algorithm in terms of PDR, delay, encryption time, decryption time, Throughput, and Computation cost is found to be very appealing.</p>