Deep-sea diving is an underwater activity that allows divers to explore the ocean's depths, typically beyond 60 feet. Divers use specialized equipment, such as scuba gear or submersibles, to breathe and navigate in high-pressure environments. This activity is essential for scientific research, marine biology, and underwater exploration. Safety is a crucial aspect of deep-sea diving, as divers must be trained to handle potential hazards like decompression sickness and equipment failure. Organizations like the Professional Association of Diving Instructors (PADI) provide certification courses to ensure divers are well-prepared for the challenges of deep-sea environments.