• UAV swarms are integral to 6G networks, merging sensing and communication to achieve full coverage and the Internet of Intelligence.
• Key challenges from low-slow-small characteristics, high density, complex low-altitude environments, and swarm coordination are analyzed.
• The paper proposes 'Ten Ones' performance metrics tailored to low-altitude UAV swarm ISAC systems.
• Promising technologies include XL-MIMO, sparse time-frequency resource allocation, channel knowledge maps, and UAV swarms as airborne ISAC platforms.