The paper introduces a novel pump that works in a similar hydrodynamic principle as an axial piston pump, but different in that the new pump employs a unique concept of Side-Intake of water (fluid) which allows it to achieve a capacity coefficient much greater than existing pumps. Based on its working principle and applications for either marine propulsors or pumps, this new system is referred to as Side-Intake Marine Impulsive Thruster/Positive Displacement Pump of Ultra-High Capacity (SI-MIT/PDPUHC). The paper presents in detail the concept of the Side-Intake of water in SI-MIT/PDPUHC and a compact design of SI-MIT/PDPUHC for its practical utilization. An evaluation of SI-MIT/PDPUHC from efficiency, linearity, and effectiveness perspectives is provided. The approach for the evaluation is based on the analysis from the fundamental principles in fluid mechanics, and supported by marine animals, laboratory findings and existing industry systems.