Forces News has been granted exclusive access into how the Royal Navy is helping the Joint Expeditionary Force (JEF) nations to respond to threats to the region.
In total, 20 ships from nine different nations are taking part in Baltic Protector, including 3,000 personnel.
The deployment, led by HMS Albion, is one of the biggest of its kind since the First World War.
It is the first training deployment of the UK-led JEF.
Brigadier Matt Jackson, Commander of Royal Marines 3 Commando Brigade, said it is about testing the allies' ability to "work together in the event of any crisis".
With Baltic Protector operating close to Russian waters, sailors said they are aware of potential threats.
"In international waters, just like in international airspace, everybody has the right to operate there by sea and by air," said Commodore James Parkin, commander of the amphibious task group.
"So, we have a right to be in the high seas, just like Russia.
"I'm absolutely certain we will see them operating in the Baltic, they are a Baltic state, just like many of the JEF nations are.
"I'm also certain any interaction will be safe, professional and cordial."
Baltic Protector has also given Royal Marines the chance to sharpen their amphibious capability.
Alongside Danish and Norwegian forces, they are practising helicopter raids, dealing with vehicle ambushes, urban combat, parachute drops and also live firing.
Over the coming weeks, JEF will conduct more training as part of the wider mission, Operation Cabrit.
The task group will go on to work alongside more NATO allies on Exercise Baltops before linking up with land forces, including a UK-led battlegroup, in the eastern Baltic.