US Navy SEALs performed an exercise with a nuclear-powered guided missile submarine in the Mediterranean Sea, as demonstrated in vivid images released by the Department of Defense. 

The US Department of Defense has released images of a special forces exercise involving Navy SEALs and a US Navy nuclear-powered guided missile submarine (SSGN), the USS Florida. The exercise took place on February 26 in the Mediterranean Sea, but the images were only released on March 17. The images show the SEALs being winched down onto the submarine from a CV-22 Osprey, and later landing a Combat Rubber Raiding Craft (CRRC) aboard the submarine with Greek Special Operations Forces (SOF). The exercise was designed to demonstrate the US European Command’s ability to deploy special operations forces throughout the theatre at a time and place of its choosing, and its commitment to training with allies and partners. The USS Florida is one of four SSGNs in the Navy and is known for its ability to carry special operators into contested environments and work as command-and-control centers for those missions. 

Source: https://www.thedrive.com/the-war-zone/navy-seals-boarding-submarine-via-osprey-seen-in-stunning-photos