One of the duties for marines is carrying out foot patrols in Sangin Bazaar
In April, 600 Royal Marines from 40 Commando were deployed to Sangin in the Helmand Province in Afghanistan.
Over the past few weeks, five marines have lost their lives taking the total number of service people killed to 293.
The unit is one of four ground holding battle groups spread out across Helmand Province, a Taliban stronghold.
They've been carrying out foot patrols in Sangin, protecting the Kajaki reservoir and preparing for operations at their main base, Camp Bastion.
Patrolling the Sangin Bazaar is one of the roles for marines during this deployment.
Capt Dom Rogers, the head of the Police Mentoring Team in southern Afghanistan, said: "We tend to go out on mixed patrols with the ANP [Afghan National Police] so taking anything between two and six Afghan police at any one time, with almost a ratio of one to one, but not always achieving that.
"We stop off at police check points, making sure they're doing their job correctly, conducting joint check points and vehicle check points in the main ingress and egress routes into the Sangin Bazaar."
He says marines are building relations with traders at the market place which is considered to be the "jewel in the crown" of operations in Sangin.
"It is a thriving environment, it's very busy and chaotic at times with the number of motorcycles, cars, kids talking to you and trying to get your attention when they're zooming past you.
"It's hard to patrol but by keeping a low force posture and reacting to the atmospherics of the people you can limit the impact you have so people can safely go about their daily business."
'Freedom of movement'
Another area where marines are based is the strategic Kajaki reservoir, which irrigates 650,000 acres of land.
The reservoir currently provides 33 megawatts of electricity and will provide even more once the British turbine delivered there in 2008 is fully installed.
Marine Rich Bartle is one of those on boat patrol.
"It gives you freedom of movement. We can get gun lines into position that we wouldn't normally be able to get on the ground so it gives the lads on the ground that extra bit of support."