Marine aerial-underwater communication remains a key challenge due to the low data rates and limited range of traditional acoustic systems, despite the vastness of the ocean. This research presents a biomimetic, hand-launched Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicle (UAV), serving as a modular communication node for water entry, underwater navigation, and airborne relaying. It features variable-sweep wings and a morphing empennage to optimize lift-to-drag ratio and stability across different flight modes, along with hybrid jet-flap control surfaces and embedded underwater jet propulsion. Computational Fluid Dynamics (CFD) analyses using panel-method and lattice-Boltzmann techniques evaluate its aerodynamic performance during launch, medium-transition, and cruise phases, showing a maximum L/D of 17 at 50 m/s and 5° angle of attack, with stable pitch control. Structural integrity under +3 g pull-up, +1 g water entry shocks, and + 1 g cruising conditions was confirmed through ANSYS finite-element static testing, indicating stresses and displacements within carbon-fiber composite limits. The design’s quick deployment, multi-mission flexibility, and validated performance establish a systematic approach for deploying hand-launched VTOL systems in large-scale maritime communication networks, progressing integrated “space-air-ground-sea” infrastructure.