Royal Marines have been training in the Scottish Highlands ahead of a deployment to the Arctic.
Personnel from 45 Commando have been undergoing mountain warfare exercises in the Cairngorms prior to deploying to Norway for cold weather training in January.
The Arbroath-based amphibious force has been honing their basic commando skills and building up an understanding of the mountain environment.
Captain Olly Frost, Officer Commanding Recce Troop, said: "Fighting in the mountains is difficult.
"The resilience and mental strength of those who deploy will be tested from day one.
"My team is here to train and ensure the commandos of the brigade can live, move, and fight in the mountains. This exercise is infamous for its difficulty."
The training also saw the personnel test Future Commando Force tactics and techniques, including working in small teams on mountain raids, the Navy said.
There was a refresher in navigation techniques and strategies, dealing with the changeable weather conditions and tough terrain, as well as tactical drills such as vertical assaults on cliff faces.
The Future Commando Force is designed to modernise the way Royal Marines operate.
It has been described by the Royal Navy as the most significant transformation and rebranding programme since the Second World War.
The marines also practised their casualty evacuation skills and 'Extraction Under Fire’ – withdrawing from combat under pressure from an adversary – while raiding 'enemy' positions.
45 Commando spent the first few months of this year testing themselves in the Arctic and are expected to return early next year as part of the UK's commitment to security in the High North.
The final phase of training will culminate in an intensive field exercise, the Navy said.
Cover image: Royal Marines train in the Scottish Highlands (Picture: Royal Navy).