Vast midwater regions away from the surface and coasts remain largely unexplored and sparsely sampled, both temporally and spatially. This project develops biohybrid jellyfish instrumented with pressure and temperature sensors as a novel, low-cost platform for oceanographic measurement, addressing limitations of traditional methods such as ships, buoys, and autonomous underwater vehicles. Biohybrid jellyfish leverage natural propulsion and pressure tolerance to enable low-energy, scalable ocean monitoring. By electronically controlling their swimming, jellyfish can be directed for targeted environmental measurements. This research focuses on four species: Aurelia aurita (moon jelly), Cassiopeia sp. (upside-down jellyfish), Chrysaora sp. (sea nettle), and Mastigias sp. (lagoon jellyfish) that encompass a spectrum of distinct jellyfish morphologies and ecological adaptations. Field studies will occur in the Florida Keys, Cape Cod, and southern California in order to test the efficacy of biohybrids across different oceanic and environmental regimes. Activities are planned for engaging a broad audience including K-12 schools, undergraduate and graduate students, and the general public. The bioinspired robots would provide opportunities for K-12 students to learn about the principle of operation and hands-on experience on neural control. The project offers interdisciplinary training for early-career researchers in biology, engineering, and environmental sensing. This multidisci