A lifeguard supervises the safety and rescue of swimmers, surfers, and other water sports participants such as in a swimming pool, water park, or beach. Lifeguards are strong swimmers and trained in CPR/AED first aid, certified in water rescue using a variety of aids and equipment depending on requirements of their particular venue. In some areas, lifeguards are part of the emergency services system to incidents and in some communities, the lifeguard service also carries out mountain rescues, or may function as the primary EMS provider.