It is part of the UK's contribution to the Joint Expeditionary Force (JEF) which encompasses nine nations from northern Europe at a time of increased threat.
At the lead of this task force is amphibious assault ship HMS Albion.
Troops from all nations have been working together, enhancing their skills, and using the military buzz word, focussing on their 'interoperability'.
Commander of 3 Commando Brigade, Brigadier Matt Jackson, said it's also been a chance for the Royal Marines to "regenerate their amphibious skills".
He added: "There's been a little bit of doubt in our minds, or the nation's minds, about whether it wants to keep it [amphibious capability] but I think that those [questions] have been answered by the previous defence secretary, so there has been very clear signals that the nation wants, in the future, to have an amphibious capability and that's what this exercise is about."
Away from HMS Albion, Arbroath-based 45 Commando took to Danish ground to practice their assault skills, with reservists from the Danish Home Guard playing the role of the enemy.
As the UK's enhanced Chemical Biological Radiological and Nuclear generalists (CBRN), 45 Commando's response to chemical attacks was also tested.
The scenario involved the commandos dealing with a chemical laboratory under the watchful eye of professionals from the Defence Science and Technology Laboratory (DSTL) who have spent time training the marines prior to now.
Experts from the DSTL joined the deployment to provide realistic CBRN scenarios and advise UK troops.
Captain Oliver Crow said the troops stormed an urban area with a "known complex production facility" where they had to "confirm and identify a chemical agent".
When dealing with potentially lethal chemicals, the marines must dress accordingly.
Marine Sam Taylor said: "You've got to be prepared for every eventuality so these suits are rated for every single chemical that's out there.
"You're sweating anyway, you're having a tough time, and then you put the kit on and you can't sweat anymore.
"I don't want to know what's on the inside of this suit anymore!"
The assault was designed to test the marines' ability to communicate and work alongside allies in different situations.
However, it was not only about operating on land - 30 Commando's Surveillance and Reconnaissance Squadron has been working with the Commando Helicopter Force in 'helocasting'.
It is a technique used by special forces around the world and requires troops to jump from a helicopter into the sea with minimal kit.
Once in the water, some of the marines had to swim to small inflatable boats before practising surf drills.
But for the rest, as part of the Landing Craft Coxswain's specialist training, they had to swim ashore in the chilly waters.