Intelligence agencies spy on us, and Trevor Paglen spies on them. His images, on show at the Photographers’ Gallery, shine a light on the shadow world of government surveillance

The first thing that strikes you about Trevor Paglen’s photographs are the colours: royal blue, dusky pink, maroon. His landscapes of sea and sky revel in bold hues – but look closer, and you’ll realise there’s more to his pictures than pretty colours. Snaking its way through a murky swathe of seaweed green is what looks like a garden hose; a black speck on a livid sky appears to be a distant bird. These aren’t mistakes that wandered into Paglen’s viewfinder: they’re the main attraction.

An award-winning photographer, Paglen has spent his career documenting the clandestine infrastructure of mass surveillance. He has traced underwater fibre-optic cables that have been tapped by the NSA , captured the flight paths of passing drones and shot secret government buildings at night. (Laura Poitras drew on his work for “Citizenfour”, her 2014 documentary about Edward Snowden.)

Paglen’s Deutsche Börse Prize-nominated exhibition “The Octopus”, at the Photographers’ Gallery in London, brings these strands together in order to shine a light on the shadow world of illicit reconnaisance. That bird in Paglen’s livid sky is actually a drone; that garden hose a tapped submarine cable. These are the eyes and ears of our intelligence agencies, and they can see and hear everything, Paglen’s images seem to suggest.

Yet, if the NSA is spying on us, Paglen is undoubtedly spying on them. Using the telescopes and lenses of an astronomer, he makes visible the places and objects intelligence agencies want to keep invisible. Though Paglen can only get so close: turning his lens up to the sky or down to the ocean depths, he shoots his subjects from miles away and uses long exposures. The results are often blurry and impressionistic: huge fields of colour dominate his canvases. Paglen, then, presents us with a challenge. Don’t be seduced by the beautiful colours and shapes in these images. Look with suspicion: not everything is what it seems.

Globenet, NSA/GCHQ-Tapped Undersea Cable, Atlantic Ocean (2015)

Most of the world’s internet traffic (95%) travels through garden hoses – or fibre-optic cables – like this one, and the NSA and GCHQ is eavesdropping on many of them. A list of tapped cables was included in the cache of documents Snowden leaked in 2013. Paglen cross-referenced this list with maritime charts to pinpoint locations on the seafloor where these cables are visible. Then he learned to scuba dive.

NSA -Tapped Fiber Optic Cable Landing Site, Marseille, France (2015)

With its luminous pink and periwinkle, this image has the feel of a watercolour. But things aren’t as transparent as they look. This view of Marseille depicts a “landing site”, where undersea cables arrive on shore. The picture appears in the exhibition next to a maritime chart called “Approaches to Marseille”, which shows the paths taken by the cables there. Surveillance is made possible by a physical network, it turns out, and this network can be mapped.

National Reconnaissance Office, Chantilly, Virginia (2014)

If this physical surveillance network had a capital, it would be Virginia. Paglen chartered a helicopter to shoot the National Reconnaissance Office (pictured), the NSA and the National Geospatial Agency at night. His images, which glow as if they were film stills from “Tron”, are in the public domain, available for anyone to use.

They Watch the Moon (2010)

This emerald city is a classified “listening station” in the forests of West Virginia. What is it listening to? Communications signals that escape into space, collide with the Moon and get reflected back to Earth. A “Moon bounce”, as it’s called, for spooks.

Untitled (Reaper Drone) (2010)

In the Nevada desert, not far from Las Vegas, there is a small military base where pilots use satellite-control to fly drones. In 2010, Paglen decided to go drone-hunting. He went to that desert, and pointed his lens skyward. If you look in the lower right-hand corner of this picture, you’ll see what his camera caught: a Reaper drone.

PAN (Unknown; USA-207) (2010-11)

These aren’t shooting stars, they’re spacecraft in Earth’s orbit. This is from Paglen’s series “The Other Night Sky”, in which he tracked and photographed classified American satellites. The streaks of light, the result of a long exposure, are the paths taken by the spacecraft as they fly around the planet, awaiting orders from their masters down below, and watching, always watching. Could PAN be short for Panopticon?

Deutsche Börse Photography Foundation Prize 2016 the Photographers’ Gallery, until July 3rd. Trevor Paglen will talk about his work at the gallery on May 31st. To find out more about his work, go to his website