In the current years, Underwater Mobile Ad hoc Network (UWMANET) has emerged as an enthusiastic field for supporting disaster prevention applications (Climate and Weather Observation, Earthquakes in Ocean (Tsunamis), underwater level navigation and tracking). In UWMANET, conventional data transmission methods have certain drawbacks such as high energy consumption, packet loss rate and end-toend delay. Nowadays, mobile node i.e. Autonomous Underwater Vehicle (AUV) is widely used for data collection from underwater sensors, which act as a relay between sensor node and surface sink. Security is a significant issue in UWMANET, which is required for secure communications. In this paper, Energy Efficient Secure Cluster based Routing Protocol called E2 -SCRP is presented in 3D UWMANET environment. The qu-Vanstone based Elliptic Curve Cryptography (qV-ECC) based short-term public key generation scheme is proposed for sensor node authentication. To reduce energy consumption, layer based clustering algorithm is proposed using Type-2 Fuzzy Logic System (T2fls) where Trust value, Distance between neighbors, Relative mobility and Node buffer size for cluster head (CH) election are considered. Next step is to execute two different security schemes based on Event Management. For event occurred clusters, Ciphertext Stealing Technique (CST) is used to resolve the ciphertext expansion problem. For normal data transmission, Lightweight Digital Watermarking (LDW) with Firefly algorithm is proposed. Optimal route for data transmission is executed by Pigeons Swarm Optimization (PiSO) and the forward to sink node via Adjacent AUV. Experiments conducted using NS3 (3.26) and the performance is evaluated for several metrics include packet delivery ratio, energy consumption, end-to-end delay, security strength, and throughput