The deep ocean biome is inversely defined by light. Sunlight penetrates only a few hundred meters below the ocean surface, a layer known as the sunlight zone. In this narrow layer almost all known ocean life occurs, as photosynthesis and mineral-rich water produces diverse plant-life. As the level of incidental light drops below one percent, the sunlight zone gives way to the twilight zone. Photosynthesis is still possible at these depths but below approximately 1000 meters there is no light at all. This darkness is known as the midnight zone. Extending in some places as deep as six kilometers to the ocean floor, life that exists here is almost entirely unknown to humans. Approximately one fifth of the ocean floor has been topographically imaged using sonar and lidar technologies, and as such we have very little knowledge of the largest ecosystem on the planet. Scientists estimate more is known about outer space than the abyssal zones of the ocean. Oceanic ecosystems keep the land-bound biome of the planet habitable. Regulating air quality through carbon sequestration, the oceans determine weather and climate. Atmospheric temperatures are controlled and weather systems driven by the redistribution of heat and moisture and storage of solar radiation. Covering two thirds of the planet and providing half of its oxygen, oceans condition earthly survival.

The ocean is both vulnerable and resilient. It’s seeming impenetrability affords aggressive extraction the opportunity to pass unseen. This ‘invisibility cloak’ renders the ocean seemingly inaccessible, but it also hides the evidence of its own exploitation. The relative physical and psychological distance of off-shore extractivist activities, and the temporality of their effects from daily life, reproduces a colonial afterlife in which the violence and destruction of extraction are concealed. In this respect, the oceans might be considered the ultimate ‘frontier’ for humanity to overcome.

In March, 2020, the supertanker New Vigorous was re-routed from the Arabian peninsular to Europe via the Cape of Good Hope. The new route added several weeks and several thousand kilometres to the journey of the supertanker, but with the Suez Canal blocked by the stricken Ever Given container ship, and the slower demand for commodities due to the global coronavirus pandemic, the journey around the southern point of Africa was economically viable for the first time in decades.

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First navigated in the fifteenth century by Portuguese explorers, this southern route was the primary means of travelling by sea between Europe and Asia until the construction of the Suez Canal. In the late nineteenth century, as vast colonial empires were built on monopolised trade routes, the Suez Canal was constructed between the Arabian and the Mediterranean seas. This halved the time of sea voyage, increased profits and expanded the power of European colonial empires. The ocean around the Cape of Good Hope (a headland of the Cape Peninsula on the Atlantic coastline in South Africa), remains a busy shipping channel, facilitating trade from South and East Asia across the Indian and Atlantic oceans. However, the seas around the Cape, known historically as the “Cape of Storms”, are notoriously dangerous and are seldom used by such large vessels. Guiding vessels around these treacherous waters is a network of forty five lighthouses that illuminate nodes of the 2,800 kilometer coastline of South Africa, stretching from Jesser Point on the Indian Ocean coastline, to Port Nolloth on the Atlantic Ocean coastline close to the border with Namibia. Each lighthouse has its own unique code, a light signal rhythm that communicates to passing ships where they are at sea.

Many of the lighthouses built along the South African coastline have Fresnel lenses, which are still in use today. The Fresnel lens is a technology developed in the early nineteenth century and deployed in lighthouses for its capacity to powerfully concentrate and refract light. Designed by the French physicist and engineer, Augustin-Jean Fresnel, these lenses are constructed of mounted prisms, arranged to allow light from the lighthouse lamp to be condensed into a powerful luminous beam. A Fresnel lens has the capacity to capture and redirect oblique light allowing for visibility with the unaided eye for over thirty kilometers out to sea. Requiring less material than conventional spherical lenses, a Fresnel lens is more cost effective to produce and lighter, allowing larger lenses to be housed in the lighthouse lantern. These lenses were a significant navigational technology in the nineteenth and early twentieth century permitting safe navigation around the southern point of Africa, and facilitating the expansion of global accumulation and exploitation.

Lighthouses render the sea navigable through visibility. As a system of coastal mapping, they delineate the edge of the ocean and stand sentinel, warning of hidden reefs and submerged rock formations. Lighthouses are part of a history of making the ocean known and accessible, an infrastructure of enlightenment rationality and its attendant violence that opened up new ‘frontiers’. Aided by the light refracted from the Fresnel lens, lighthouses reached greater distances and depths of visibility than ever before, thereby enabling fluid imperial and capitalist trade and expansion.

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Filipa César and Louis Henderson in their film essay Sunstone (2017) situate the development of lighthouses within a European Enlightenment rationality through the instrument of the Fresnel lens. Through the use of analogue 16mm film and computer generated images the film charts technologies from historical methods of optical navigation to contemporary positioning algorithms. These technologies are inscribed through the film’s materiality and mechanics. “Light in Sunstone emerges as a material substrate of various intersections of navigation and legibility in contemporary image-based communications capitalism. Only a materialist analysis of light, which the film proposes and advances, could account for its actions.” ¹

In her 16mm film Disappearance at Sea (1996) Tacita Dean documents nightfall and uses the refraction of light through the Fresnel lens of the St. Abb’s Head Lighthouse in Scotland and its surrounding landscape to reflect on the spectacle of projection. Indoing so Dean foregrounds the medium of analogue film and instruments of observation, film and cinema itself. Dean’s film takes as its starting point the tragic narrative of Donald Crowhurst, an inexperienced yachtsman who particpated in the 1968 Sunday Times Golden Globe Race to solo circumnavigate around the world. Crowhurst ran into difficulties and eventually his boat, the Teignmouth Electron, was found abandoned. Crowhurst’s dissapearance at sea is compelling as it speaks to a existential anxiety about the sea’s capacity to make things vanish without a trace. From the vantage point of the lighthouse lantern, Dean’s meditative film is suggestive of the darkness the sea represents mirrored in the sunset and darkness the film documents. The lighthouse sits ambiguiously between the history of infrastructures of enlightenment rationality and the primordial fear that the ocean is in excess of the human.

The first undersea telecommunication cables were laid in the 1850’s, and by the end of the century all the world's continents were connected by undersea cables. The first fibre optic cables were laid under the oceans in the 1980’s. Now, over 880,000km of undersea fibre optic cables carry around ninety-nine percent of global communication through the emission of small pulses of light that travel along millimetre-thin glass threads. ² These cables are laid across parts of the ocean floor about which scientists know almost nothing, and which themselves are so deep that sunlight cannot penetrate. The routes of these cables are not outside of history, “[c]onservative and yet resilient, they have followed paths that are tried and true, often following the contours of earlier networks, layered on top of earlier telegraph and telephone cables, power systems, lines of cultural migration, and trade routes.” ³

The very material infrastructure of submarine fibre optic cables follows the same trajectories as the colonial trans-atlantic slave trade routes, reinscribing what was known historically as ‘the triangular trade’. Here the colonial and neo-colonial frontier shifted from the physical possession of peoples, lands and resources to the control of access to digital technologies, in order to both maintain and expand dominance over the Global South. The routes through which Africa was thrust into a globalised colonial geography are the same routes through which Africa’s connection into a globalised digital world is framed. Artist Tabita Rezaire’s film Deep Down Tidal (2017) considers the ocean as a substrate for communication networks. Deep Down Tidal reflects on the virtual made manifest in the physical infrastructure of submarine fibre optic cables that transfer digital information, and how these cables follow the contours and trajectories of colonial and slave trade routes. For Rezaire, the fibre optic cables are a material architecture of a digital colonialism.

Alongside this infrastructure of global digital capitalism are what is known as dark fibre – those unused or broken parts of the framework that are abandoned or forgotten. By making use of this excess dark fibre, scientists have recently been able to map parts of the ocean floor, tracing the refraction of light particles off microscopic fractures and creases in the optic cables.

Deep-sea mining is the process of extracting mineral deposits from below the ocean floor, specifically the area of the ocean below two hundred metres in depth. This area covers approximately sixty-five percent of the earth’s surface. Until recently, the emphasis has largely been on exploring the deep sea, locating, assessing and evaluating the mineral deposits for exploitation. But the rising demand for depleted land based deposits of metals such as copper, nickel, aluminium, manganese, zinc, lithium and cobalt, coupled with the advancement of imaging and extractive technologies, have made mining in the deep ocean increasingly financially viable. Geographically, the deposits are described as being between known geographies or through measures of distance between locations. For example, the Pacific Ocean between Mexico and Hawaii is an area called the Clarion Clipperton Fracture Zone, an abyssal plain that is 4.5 million square kilometers between Hawaii and Mexico. Most of these deposits fall within what are referred to as international waters.

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The International Seabed Authority (ISA), an intergovernmental body set up in 1994 to oversee and control mining beyond any one country’s jurisdiction, was established as part of the United Nations Convention on the Law of the Sea. However there are no specific sanctions for contravening the ISA protocols and several nations, including the United States of America, are not signatories. ⁴ In September 2021 at the International Union for the Conservation of Nature (IUCN), eighty-one governments or government agencies voted to support a moratorium on deep ocean mining.

Deep sea mining, fracking, and ocean floor trawling are predicated on invisibility in two ways: firstly, in their attempts to extract what can’t be seen by the unaided eye, and secondly in the effective invisibility afforded by the ocean in these extractions and their aftermaths. In Prospecting Ocean, curator and writer Stefanie Hessler writes: "Deep sea mining is hidden from plain sight as it occurs in sites that are located several thousand meters below sea level (...) Their representation as faraway places is intended to make the environmental effects of extraction seem negligible to Western investors and publics.” ⁵ One of the proposed methods of mining is the ‘harvesting’ of polymetallic nodules that accumulate on the ocean floor, especially near hydrothermal vents. These ‘potato-like’ nodules are formed over millennia (some scientists estimate that they grow approximately three millimeters per million years) as a result of the rapid cooling of mineral deposits in the water. Within the space of a generation, this ‘yield’ may be extracted from an area of ocean floor the size of western Europe. Along with these nodules, the surface of the sea-bed would be stripped bare by underwater robotic machinery in a process similar to land-based strip-mining. Scientists estimate that proposed ‘harvesting’ would cause oceanic dust plumes to disrupt ocean ecosystems, impacting coral, mangrove and coastal wildlife growth. ⁶

Prospecting the deep ocean requires hydrographic surveying and imaging, which relies on technologies such as sonar (multibeam sonar systems) and remote sensing airborne and subsea light detection and ranging (Lidar). Lidar systems deploy pulsed lasers in order to visualise, measure and map ocean depths, seafloor characterisation and habitats. Lidar uses green and red light to survey the oceans above and below sea level. The green light penetrates into the water body and captures the seafloor, while the red light is reflected off the water surface. By using both colours it is possible to distinguish the water surface from the water body and ocean floor. Lidar measures topography by observing the time required for light to travel from a laser to the seafloor or water surface, reflect, and return to the sensor. Lidar imaging has the capacity to detect both geological topography and biological life. Thus this low-altitude survey system supports research undertaken by geologists and biologists alike, and this research is equally drawn on by ecologists and ocean mineral prospectors.

Stefanie Hessler reminds us that technologies and scopic regimes have evolved alongside and in service of extractive neocolonial imperial exploits, “technological advancements share a history with colonialist capitalist exploitation. As a geocentric cosmology gave way to a heliocentric worldview, and other continents were “discovered” and mapped by Europeans, new technologies like the telescope supported this change of perspective.[...] the act of looking is not uncoupled from interest, but on the contrary, serves protectionist or expansionist aims. ⁷ (…) [T]echnologies of observation are not passive but come about in conjunction with the observed. Power is dependent on and emanates from instruments involved in observation and categorization. As part of observation, judgement, and examination, the technologies of seeing exert control over the seen.” ⁸

What is mapped and visualised by these optical technologies is only ever partial as visualisations are translations that convey what escapes both light and human perception. What is omitted is the ecological life and ecosystems that exceed these imaging technologies. Only the areas of the hydrosphere that are deemed relevant for exploit are honed in on for observation, often to the exclusion of the surrounding area. Percieved in isolation, the deep sea floor is removed from its vital relations within the ocean that exceed the image frame and the scope of extractivist projects. Critically, visibility and invisibility in exploitative projects enable both extraction and preservation. The existence of unquantifiable lifeforms yet to be studied and documented in the deep sea is a measure of the ocean’s protective and concealing capacities.What remains unseen is safe from exploitation. However enlightenment logic – to see is to know – and the relative invisibility, remoteness and the temporal delay in perceiving or experiencing the effects of deep sea mining, benefit the extraction industry.

The deep sea biome, constituted by the twilight zone, the midnight zone, the abyss and the trenches, is a dark, cold and pressurised environment which no sunlight can reach, and as such is an area beneath which no photosynthesis can take place. Many animals and organisms in the midnight zone emit their own light through their ability to produce bioluminescence, a chemical reaction deployed to attract a mate, lure prey, and to defend and camouflage themselves. Bioluminesence is a chemical reaction produced by symbiotic bacteria within cells called photophores which emit light. Bioluminescence produced in the ocean is a spectrum of blue-green light which has shorter wavelengths and can travel and be perceived in deep waters. Understood as a form of communication in the ocean, scientists estimate that almost ninety percent of all deep sea animals have bioluminescence ⁹ and further estimate that in this area, nearly all of the species that are collected “are new to science.” ¹⁰

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One of the lifeforms living deepest in the ocean is the sea cucumber. Sea cucumbers constitute 90% of the deep sea ecosystem biomass and could be considered the dominant marine lifeform. ¹¹ Sea cucumbers feed on the seabed itself, ingesting sedimented plankton and living and dead organisms, and excreting sand that is free of organic matter. This is vital for the health of the seabed. By removing dead organic matter, they prevent excessive oxygen depletion in the depths while releasing nutrients on the ocean surface. This enables the growth of microalgae with which all marine food chains begin. The swimming sea cucumber has the ability to deploy bioluminescence which is ejected onto a predator in order to visualise a predator. The light is produced upon physical contact by another animal.

The deep ocean’s ecosystems sustain the possibility of human existence and more-than-human life while its extreme conditions and impenetrability allow for opportunities both for the protection of the oceans from extractivist regimes and for cover while its depths are exploited. Metaphors of light, and its absence, are frequently used to situate the relationship of humans to the deep ocean. Enlightenment ontologies regard light as illumination and progress, as legibility and knowledge. These logics can also be deployed to facilitate violence and exploitation. Aided by the light refracted from the Fresnel lens, lighthouses reached greater distances and depths of visibility across the ocean surface thereby creating the conditions for the possibility of fluid colonial, military and capitalist trade and expansion. On the ocean floor, the networked infrastructure of fibre optic cables communicates information in the form of pulses of light. These navigational instruments and technologies of communication signal how colonial gestures of discovery and possession are connected to acts of seeing and the production of knowledge, the projection of light and enlightenment epistemologies. In the deep ocean where sunlight cannot penetrate, forms of social life amongst animals have an altogether alterior connection to light. The ocean’s microbial ecosystems and deep ocean life escape and exceed efforts at visualisation and conceive of light differently; relationally. Light on the ocean floor is fleeting, seductive, dangerous, intimate and ecstatic. Deep sea research and prospecting has begun illuminating these ecosystems, long hidden from human sight, from human knowledge, from human destruction.

Amy Watson is an independent curator and a founding director of POOL, a Johannesburg based not-for-profit art organisation that supports practitioners through collaboration, commissioning, and the production and presentation of new work. Most recently she curated How To Disappear (2020) and Soft Architectures (2019) at Goodman Gallery, Johannesburg and Cape Town.