Joint Warrior - the bi-annual military exercise - will bring 5,700 military personnel from armed forces across the world to the seas around Skye over the coming days.
Countries taking part include Norway, Sweden, Germany and the USA as well as those from the UK.
Some thirty-one warships and submarines as well almost 70 aircraft, many of them being flown out of RAF Lossiemouth in Moray and Prestwick in Ayrshire, are being used in the training off the Scottish coast.
Running until October 20 , a Royal Navy spokesperson said: Joint Warrior is a major bi-annual (spring and autumn) multi-national exercise which takes place in the Scottish Exercise Areas.
Planned and co-ordinated by Northwood staff it is facilitated through Faslane which is used as the Headquarters throughout the exercise. Much of the activity occurs well offshore, however, local marine users should be aware of elements of the exercise which they may encounter.
"Joint Warrior (JW) 162, will take place October and will comprise of a programme of exercises conducted by land forces, warships, submarines and aircraft across the UK. The maritime element is focussed in the offshore and coastal waters to the north east, north and north west of Scotland."