Welcome back to the Photo Of The Day, daily article series where we take a look at some of the best firearm-related pictures. Above you can see a U.S. Marine with Charlie Company, 1st Battalion, 6th Marine Regiment shooting an M32 grenade launcher on the flight deck of the USS San Antonio. This happened as the ship crossed the Atlantic Ocean on its way to the exercise BALTOPS 2015. Seventeen NATO and partner nations participated in the 43rd iteration of this multinational maritime exercise in Poland, Sweden, Germany, and throughout the Baltic Sea.

Below: NATO Response Force and Allied Marines from the U.K., U.S., Sweden, and Finland simulate amphibious assaults on a Swedish beachhead during BALTOPS 2015.

This is the CB90-class fast assault craft, with a Swedish flag.

A Finnish Marine secures the perimeter for extraction to a Polish amphibious assault vehicle on a Swedish beachhead during BALTOPS 2015, June 11. BALTOPS is an annual, multinational exercise designed to enhance the operational familiarity of NATO Allies and partner nations and demonstrate the capabilities to defend the Baltic region.

A U.K. Royal Marine Commando fast-ropes into a drop zone on a Swedish beachhead

A U.K. Royal Marine Commando gives feedback to Finnish Marines after they simulated an amphibious assault on a Swedish beachhead during BALTOPS 2015,

Photos by Sgt. Tatum Vayavananda.