Slædepatruljen Sirius (Sirius Sledge Patrol) or informally Siriuspatruljen (Sirius Patrol) is a unique elite Danish navy unit that conducts long-range reconnaissance patrolling, and enforces Danish sovereignty in the arctic wilderness of Northern, and Eastern Greenland, an area that includes the largest national park in the world. Patrolling is usually done in pairs, sometimes for 4 months often without additional human contact.