SUBMERSE: turning submarine telecommunications cables into planetary sensors.

The internet relies on submarine telecommunication cables that criss-cross our oceans, connecting countries and continents. Yet, the oceans remain among the most underexplored areas of our planet. The SUBMERSE project (SUBMarinE cables for ReSearch and Exploration) aims to utilise existing technologies to retrofit fibre optic cables as sensors for monitoring planetary processes beneath the waves, achieved by attaching fibre optic interrogators at landing stations.Running for over two years, the project has achieved notable successes in developing innovative technologies and analytical techniques. These advancements have expanded the use of telecommunication cables for fibre sensing and enabled the creation of data products, primarily in geoscience and marine science.For instance, we have developed an automated, machine-learning-based algorithm for analysing earthquake waveforms and measuring ocean surface gravity waves using seafloor Distributed Acoustic Sensor (DAS) recordings. Furthermore, new DAS technologies have been introduced, such as the ability to monitor relative temperature changes via submarine cable fibres. The project has also demonstrated the harmonious coexistence of DAS with active telecommunications traffic on the same fibre and successfully deployed state-of-polarisation (SOP) measurements synchronised with an atomic clock in one of the most remote locations in the world.However, geopolitical events and incidents involving suspected targeting of critical submarine infrastructure have posed challenges to international data sharing. While adhering to the FAIR principles, we address the evolving complexities of sharing data that may contain sensitive information alongside valuable research content. To mitigate these risks, we have implemented robust AI software and processes to securely clear data for research purposes.This presentation will detail the activities, achievements, and challenges of the SUBMERSE project, which strives to develop a pilot research instrument and provide a blueprint for continuous monitoring of Earth's systems across and between continents.