Evaluate the technological maturity of sensor systems. Associated Task 3.1. Engineering specifications and technological maturity; Leader: IFREMER; Duration: M6-M12 The underwater sensing objectives refined by WP 1 will determine the required performance in precision, deployment duration and pressure of the new sensors and general specifications will be issued. The Technology Readiness Level (TRL) will be evaluated for each of the NeXOS sensor systems, leading to basic engineering specifications so that performance can be demonstrated within the duration of the project. The TRL study will use remote interviews and meetings among the NeXOS consortium (including referenced providers) and related projects (EuroARGO, EMSO/ESONET, JERICO, GROOM, etc). It will be based on common practice for sensor choice and enhancement and will critically review the limits and achievements of existing sensors within the market.