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Into the deep

The subsea is drastically under sampled. Margaret Leinen discusses the potential for the Ocean Internet of Things to revolutionise our understanding of the ocean

Words by Margaret Leinen
1 September 2022

It is often said that we know more about the surface of the Moon or Mars than we know about Earth’s seafloor. Technological advances are set to transform our understanding of the ocean and its seafloor as we work towards building an Ocean Internet of Things (OIT) – a subsea network of devices, including sensors and remote and autonomous underwater vehicles, that are dispersed throughout the ocean globally and can communicate with each other and with us. 

As Margaret Leinen, Director of Scripps Institution of Oceanography, USA, explains, this idea of a ‘smart ocean’ “extends the concept that we’ve come to know for internet-enabled communication between devices in our homes (‘smart homes’) or cities (‘smart cities’) to the ocean.”

Grand challenges

To address many of the grand challenges we face, including climate change, ocean acidification, declining biodiversity and escalating resource demands, as well as geohazards and georesilience, we must drastically increase our measurements and sampling of the ocean globally. 

“Many of the ocean processes that are involved with climate change, like ocean circulation, evolve slowly over years. Others, like acidification are patchy and difficult to characterize from a few scattered measurements. Plate tectonic processes are often a combination of slow, small changes and much larger rapid changes. The slow changes require substantial time to observe, while the rapid changes require luck to measure unless you have persistent measurement devices in place. Taking samples frequently (as opposed to measurements) requires storage and might result in analysing samples that record little variation for a long time.”

In theory, continuously operating sensors would generate vast datasets and could beam back data in real-time allowing us to monitor the ocean in a similar way to a national weather service.

“One of the most important characteristics of an OIT is that it would allow us to make measurements without having to be at the site. We could make measurements more cheaply without use of ships and could occupy locations longer – or even continuously. We could make many more measurements. 

“We could also have one system of sensors or samplers controlled by measurements from another system. The ‘smart ocean’ will allow sensing and measurement devices to talk with each other and exchange information, or control actions like sampling. For example, an OIT that activates sampling when measurements detect a certain magnitude of change in some variables would capture samples from large events.”

To cite a more specific example, the OIT could transform our understanding of the biological evolution of the ocean. In particular, Margaret is excited about the application of technology developed for genomic analysis to marine environments. 

“Metagenomics and environmental DNA (eDNA) hold promise of being able to rapidly assess the presence and abundance of taxa in the ocean from analysis of water samples rather than having to collect organisms. We can now sample for biomolecules from autonomous vehicles and oceanographers are working to develop instruments that can analyse samples onboard. I imagine a network of platforms having instruments that analyse the biology of the ocean at scale and can begin to understand in detail how it is changing with time.”

Many are hard at work on solving this problem. Most solutions use fibreoptic cables, which can carry large volumes of information at high speeds, but require physical cables and a means of connecting sensors or samplers to the cables 


While with the right investment we can quite rapidly build the vehicles and sensors needed to create an Ocean Internet of Things (the ‘Things’), the communication or ‘Internet’ element is harder to achieve. 

“To activate ‘smart ocean’ interactions, we need an underwater internet. This is no small challenge. On land, in the atmosphere, or in space, communication is easy using the electromagnetic spectrum. Waves, often light, carry electronic signals and allow devices to interact. But light is scattered in the ocean and does not travel far. As a result, an ocean internet has to be based on some other transmission. Sound carries exceptionally well in the ocean, but takes a lot of power to generate, is slow, and can’t carry much information. So, there are major challenges to an underwater internet system.

“Many are hard at work on solving this problem. Most solutions use fibreoptic cables, which can carry large volumes of information at high speeds, but require physical cables and a means of connecting sensors or samplers to the cables. Connected instruments can only communicate with other devices attached to cables. Other ideas are based on networks of devices that communicate with sound, but which send information to a receiver that is then linked by fibreoptic cable. Still others are based on use of autonomous vehicles that could make measurements and then go to a cable connection to send their information.”

Still, significant investment of resources is required if we are ever to create and realise the full potential of an OIT. “The biggest near-term challenge to achieving a smart ocean is the resources needed to develop and demonstrate the potential of various ocean internet technologies, to determine which are most useful, and for which conditions and types of measurement/sampling. We are currently spending comparatively little on the development of the OIT and identification of the most effective systems will take years at the rate that we are investing. 

“The longer-term challenge will be funding the OIT. Some components of the OIT, especially those that contribute to natural hazard response, may be funded sooner and more robustly than those that contribute to our understanding of other grand challenges.”

There is some concern about the potential for subsea communication systems such as sonar to disturb ocean wildlife that relies on sound for their own communication, and impacts on ocean ecosystems will need to be assessed at every stage as we develop the OIT. However, Margaret suggests that currently there isn’t so much resistance to creating the ocean internet itself, rather there is concern over the kinds of ‘things’ that might be connected to the internet. “For example, whereas a system that could track an incipient harmful algal bloom and relay warnings while the bloom was barely detectable might be welcomed, one that could identify and then guide the harvest of valuable organisms (e.g., precious coral) would be vociferously opposed.”

Future revolutions

Margaret emphasises that technical and digital advances are key to developing the OIT – both the various instruments and the infrastructure needed to create platforms and systems for that instrumentation – noting that “A previous Director of Scripps Institution of Oceanography, Roger Revelle, once said that great periods of oceanography are defined by new kinds of instrumentation that allow new insights.”

One such great period was initiated in the early 2000s with the launch of the autonomous network, Argo. This international programme uses a fleet of about 4,000 drifting floats deployed across the global ocean to observe temperature, salinity and currents. Margaret explains that Argo drastically extended our observations of temperature and salinity in time and space. Now, biogeochemical sensors are being deployed on Argo floats thereby building a more detailed understanding of the links between nutrient cycling and ocean physics. 

“Much as Argo revolutionized physical oceanography, the realization of an OIT would mark a step change in our capability to extend observations and sampling of a host of ocean environments to scale.”

Margaret Leinen
Professor Margaret Leinen is Vice Chancellor for Marine Sciences, Director of Scripps Institution of Oceanography, and Dean of the School of Marine Sciences at the Scripps Institution of Oceanography, University of California San Diego, USA. Margaret is also a member of the Decade Advisory Board, an advisory body to UNESCO’s Intergovernmental Oceanographic Commission (IOC), the UN body tasked with coordinating the Ocean Decade (www.oceandecade.org).

Margaret’s plenary talk ‘Activating the Smart Ocean’ given at the Smart Oceans conference 2020 (www.smartoceans2020.org) is available here: https://www.youtube.com/watch?v=ErHcf-VwbxE


Interview by Amy Whitchurch


Leinen, M. Into the Deep. Geoscientist 32 (3), 30-32, 2022; https://doi.org/10.1144/geosci2022-026

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