A mix of Fleet Protection Group Royal Marines
and Royal Navy personnel from HMS Portland interdict 2 vessels belonging to suspected pirates in the Gulf Of Aden. Note the Lynx HMA.8 helicopter, from HMS Portland, providing top cover for the operation. The Lynx is equipped with with a .50 caliber HMG and carries a Maritime Sniper Team who are typically armed with high-caliber sniper rifles.
more info on this incident : official MOD report