You may have noticed many naval vessels are painted grey – but why?
Grey has been the colour of Royal Navy ships for more than a century, with the colour effective at keeping a vessel from being seen in a number of different situations and reducing the clarity of vertical structures.
It also allows vessels to blend in with haze and stop easy visual identification.
Even if a ship is not near the horizon, a light grey colour scheme can make a ship tricky to see – with spotting a grey vessel even harder in foggy or cloudy weather conditions.
And, as all the ships are painted the same colour, it may delay the identification of a particular ship even after it has been sighted.
However, grey paint is only universally used for the side view of a ship, with the colour scheme of the upper decks varying, depending on the navy in question.
American ships have traditionally used a darker grey, with Russian ships using red or green.
Watch: 'Iconic new look' – HMS Tamar receives dazzle camouflage makeover.
While grey is a popular colour for Royal Navy ships, the service is able to mix it up occasionally.
Earlier this year, the Royal Navy's River-class offshore patrol vessel fleet received a new paint scheme known as 'dazzle'.
The style, consisting of contrasting shapes and colours at striking angles, was first introduced by the service in World War One, with many navies across the world following suit.
The various shapes, angles and colours were intended to confuse enemy submariners peering through periscopes, making it hard for them to identify ships and confuse their calculations about the target's speed and direction.
Dazzle camouflage was quickly phased out by the Navy after the end of the Second World War in 1945 and the improvement of radar and other technology.
Watch: HMS Severn and her 'Western Approaches' paint job.
Dazzle has some similarities to another paint scheme, known as 'Western Approaches' which itself is a mark of respect to the sailors who fought and died in the Battle of the Atlantic.
As a development of earlier Royal Navy camouflages, the scheme was first used on World War Two destroyer HMS Broke.
It was then replicated for other destroyers and small ships engaged in anti-submarine operations, designed to "hide" the vessels.
HMS Severn is among contemporary Navy ships to be painted in Western Approaches.