Ocean bottom seismometers (OBSs) are critical for imaging the Earth's interior beneath oceanic regions, which cover two-thirds of the planet. While future deployment of long-range distributed acoustic sensing (DAS) on trans-oceanic cables may expand coverage, conventional OBSs still offer superior data quality and full three-component measurements. An optimal approach would involve complemental use of OBSs, DAS, and MERMAIDs.

However, for long-term, stand-alone broadband OBSs (BBOBSs), data retrieval is a major challenge due to the need for physical recovery. Acoustic modems offer low-speed communication (~9600 bps), unsuitable for transmitting large raw datasets and are power-intensive. High-speed recovery using ROVs with optical systems like underwater mateable connectors (UMC) or laser optical modems (LOM) is possible, but these are costly and physically demanding, especially for compact BBOBSs.

To address this, we propose a low-cost short-range WiFi data link (2.4 GHz) using a soft, oil-filled plastic package between antennas to maintain alignment and reduce electromagnetic attenuation at the seafloor. This system will be tested on the BBOBS-NX, scheduled for 4-year deployment in Hyuga-nada, Japan, in 2025, alongside a new fiber strain-meter using the LOM and four standard BBOBS units.