Traditional ocean monitoring methods like buoys, ships, and satellites lack the spatial resolution, responsiveness, and mobility required for modern maritime applications. This work presents a new class of compact, self-powered autonomous ocean drones capable of distributed, persistent sensing of key environmental variables. Each unit harnesses wind, wave, and solar energy to operate without external infrastructure and communicates via a low-power mesh network for real-time data transmission. 400 h of deployment in San Francisco Bay validated autonomous navigation, environmental sensing, and system durability. This scalable platform enables high-resolution, real-time, distributed, contact-based monitoring of parameters such as waves, sea surface temperature, salinity, dissolved oxygen, chlorophyll, turbidity, and ocean currents, which is economically infeasible to be done by expensive buoys, ships and satellites and thereby supports scientific research, climate studies, and safe maritime operations.