A skin-diver is an oceanaut who dives underwater without the use of breathing apparatus. They are often referred to as free divers, and they rely on their own physical strength and breath-holding ability to explore the depths of the ocean. Skin-divers typically use a mask, fins, and snorkel to help them navigate the waters and observe marine life. They may also use a wetsuit to protect themselves from the cold temperatures of the deep sea. Skin-divers are often employed by research organizations or commercial diving companies to collect data or perform maintenance tasks.