The monitoring of currents in the abyssal ocean is an essential foundation of deep-sea research. The state-of-the-art current meter has limitations such as the requirement of a power supply for signal transduction, low pressure resistance, and a narrow measurement range. Here, we report a fully integrated, self-powered, highly sensitive deep-sea current measurement system in which the ultra-sensitive triboelectric nanogenerator harvests ocean current energy for the self-powered sensing of tiny current motions down to 0.02 m/s. Through an unconventional magnetic coupling structure, the system withstands immense hydrostatic pressure exceeding 45 MPa. A variable-spacing structure broadens the measuring range to 0.02–6.69 m/s, which is 67% wider than that of commercial alternatives. The system successfully operates at a depth of 4531 m in the South China Sea, demonstrating the record-deep operations of triboelectric nanogenerator-based sensors in deep-sea environments. Our results show promise for sustainable ocean current monitoring with higher spatiotemporal resolution.

深海洋流的监测是深海研究的重要基础。最先进的电流表存在一些局限性，例如信号传输所需的电源、耐压低以及测量范围窄等。在这里，我们报告了一种完全集成、自供电、高灵敏度的深海电流测量系统，其中超灵敏摩擦纳米发电机收集海流能量，用于自供电传感低至 0.02 m/s 的微小电流运动。通过非常规的磁力耦合结构，该系统可承受超过45 MPa的巨大静水压力。可变间距结构将测量范围扩大到 0.02–6.69 m/s，比商业替代品宽 67%。该系统在南海4531米的深度成功运行，展示了基于摩擦纳米发电机的传感器在深海环境中创纪录的深度运行。我们的结果显示了具有更高时空分辨率的可持续洋流监测的前景。