The deep-sea environment is the largest ecosystem on earth and poorly study. The lack of affordable technology and the immense size of this ecosystem, with all its different environments and habitats, such as the pelagic realm, the benthos with abyssal planes, ridges, vents, seamounts, cold seeps, sponge aggregations, cold-water corals gardens and reefs, to name just a few, contribute to the lack of knowledge.

With the increase technological development, and with the overexploitation of land and shallow water resources, humanity is migrating deeper in the sea, by extracting oil and gas, fishing on deeper grounds, extracting minerals from the continental slopes and discussing the possibility to mine seafloor massive sulphides (SMS), nodules and cobalt crusts.

In order to understand human impacts on deep-sea ecosystems and to propose strategies to mitigate these impacts, we need to comprehend the nature of the environment. Time series are crucial, for the continuous measurement of the environmental characteristics of the deep. However, studying the deep-sea is expensive. There is the need of oceanographic vessels, underwater vehicles and sensors that cannot be continuously at sea.

To bridge this gap, the scientific community has been working together with engineers to develop continuous observation systems that will allow to have time series, and to understand the natural fluctuations of the en- vironment. Fixed-point observatories exist in several key places around the globe. They can be cabled, tethered or autonomous, measuring con- tinuously or at a high frequency, and sending the data to shore, to warn about potential tsunamis, seismic crises at the bottom of the ocean, or even an increase in the deep-water turbidity.

Portugal has been involved in this effort, through the participation and usage of a fixed-point observatory installed as part of the EMSO network, Like the EMSO-Azores in the Lucky Strike hydrothermal vent(main- tained by EMSO-France) , and raising funds to install other nodes at the Gulf of Cadiz and on the Condor seamount (Azores). Observatories are used to detect climate change, monitor mining and contribute to Global Ocean Observation System.