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IDOOS

Integrated Deep Ocean Observation System

IDOOS (Integrated Deep Ocean Observation System).

IDOOS is the first continuous scientific observation infrastructure developed by the Millennium Institute of Oceanography (IMO in spanish) and the Oceanographic Instrumentation Center (CIO in spanish)to conduct integrated studies on the physical, biogeochemical, and geophysical processes of the deep ocean and hadal zone along the Chilean margin, with a particular focus on the Atacama Trench.

It integrates state-of-the-art oceanographic and geodetic monitoring technologies—complemented by a land-based seismological network—within a unified framework of interdisciplinary scientific research.

What does it observe?

 

The system is equipped with instruments and sensors that continuously monitor key variables to better understand deep-ocean dynamics, including:

  • Deep and hadal ocean currents.
  • Temperature, salinity, and pressure (CTD).
  • Dissolved oxygen (O₂).
  • Particle and sediment flux.
  • Seafloor pressure associated with tectonic deformation.

What components make up the system?

 

IDOOS consists of distinct, complementary observation systems that continuously and autonomously record data, enabling the construction of long-time series in one of the deepest and most extreme environments on the planet.

Hadal Oceanographic Mooring

A line approximately 4 km long extending from 7,700 to 4,600 m depth, equipped to observe the water column and its variability in the hadal environment:

  • 3 Aanderaa current meters (SeaGuard II and SeaGuard Hadal models).

  • 3 Sea-Bird SBE 37 CTDs installed alongside the current meters to record temperature and salinity.

  • 3 McLane Mark 78H sediment traps designed to capture vertical particle flux moving toward the depths.

  • 1 Sea-Bird SBE 19plus V2 CTD-O located near the bottom of the line to record conductivity, temperature, depth, and dissolved oxygen in the deepest part of the trench.

The second mooring is located on the continental slope, extending approximately from 3,900 to 300 m depth. Its configuration allows for observing the variability of oceanographic conditions throughout the water column and complements the observations conducted in the hadal zone.

  • 5 Sea-Bird oxygen sensors (SBE 43 model), spaced approximately every 500 m.

  • 3 Sea-Bird SBE 37 CTDs to record temperature and salinity.

  • 2 SAMI-pCO₂ sensors designed to measure the partial pressure of carbon dioxide in the ocean.

While moorings enable continuous observations over extended periods, the Lander complements these measurements by taking instruments directly to the floor of the Atacama Trench, where it collects samples and acquires ultra-high-resolution images.

The system is equipped with sensors to measure temperature, pressure, salinity, and dissolved oxygen. In addition, it incorporates an ultra-high-definition camera that captures images of the hadal environment and allows direct observation of seafloor conditions. The Lander also features two 30-liter Niskin bottles to collect water samples directly from the greatest depths of the trench for subsequent laboratory analysis.

It consists of a network of seafloor sensors that continuously and with high precision record hydrostatic pressure variations caused by vertical changes in the overlying water column.

This mechanism enables the detection of millimeter-scale displacements of the ocean floor associated with the seismic cycle and the tectonic deformation of the Chilean continental margin, providing key data for monitoring and research into subduction geodynamics.

It complements marine observations with the recording of land-based seismic activity, allowing for the integration of oceanic processes with the tectonic dynamics of the continental margin.

Scientific significance

 

One of the primary challenges in understanding the deep ocean is the scarcity of continuous, long-term observations. This limitation is particularly severe in the hadal zone, where extreme depths and hostile environmental conditions make instrument deployment and recovery technically complex tasks.

To address this challenge, IDOOS proposes an integrated observation strategy: its moorings continuously record ocean conditions across various depths, the Lander enables direct observations and sampling at the trench floor, and the bottom pressure sensor network detects changes associated with tectonic deformation along the margin.

By combining these data sources, IDOOS allows joint research into processes traditionally studied in isolation, advancing our understanding of how ocean dynamics, biogeochemical cycles, and tectonic activity interact in one of the planet's most extreme and under-explored environments. It represents a globally unique infrastructure for Hadal zone studies, establishing Chile as a benchmark in deep-ocean observation.

Milestones

 

  • 2023 – International Expedition SONNE: Deployment of the first seafloor pressure sensors (FETCH AZA) aboard the R/V SONNE.
  • 2023 – Expedition IDOOS I: Deployment of oceanographic moorings aboard the R/V Abate Molina.
  • 2024 – Expedition IDOOS II: Recovery, maintenance, and redeployment of oceanographic moorings, alongside the deployment of a lander, aboard the AGS Cabo de Hornos.
  • 2025 – Expedition IDOOS III: Acoustic data offloading (FETCH AZA), recovery of two seafloor pressure sensors, and lander deployment aboard the AGS Cabo de Hornos.
  • 2025 – Expedition DIZMO: Recovery of the Atacama Trench mooring and acoustic data offloading (FETCH AZA) aboard the AGS Cabo de Hornos, in collaboration with the Millennium Nucleus for the Study of Ocean Deoxygenation in the South Eastern Pacific (DEOXS) and the Chilean Navy.

Institutions and Funding

 

IDOOS is led by the Millennium Institute of Oceanography (IMO in spanish) and the Oceanographic Instrumentation Center (CIO in spanish) at the University of Concepción, with the participation of the University of Antofagasta, the Austral University of Chile and the Pontifical Catholic University of Valparaíso, in international collaboration with GEOMAR (Germany).

It is funded by the National Agency for Research and Development (ANID in spanish).