In this paper, an observer-based dynamic event-triggered control scheme is designed for the tracking control of Autonomous Underwater Vehicle (AUV) with system uncertainties, external disturbances and limited communication. Firstly, a neural network extended state observer is designed to estimate the system uncertainties and external disturbances online. Then, a dynamic event-triggered controller is designed for the tracking control of the AUV to reduce the communication burden while also reducing the actuator wear and tear. Furthermore, the introduction of dynamic variables in the event-triggered mechanism can reduce the number of triggers. It is proved that all the signals in the closed-loop system are uniformly ultimately bounded, and the Zeno behavior is excluded. Finally, some simulations are demonstrated to verify the effectiveness of the proposed control scheme.