chances of a successful rescue. Full face masks are more effective, bit more complex and expensive. Mouthpiece retaining straps are not as effective but are inexpensive and simple to use. These measures have not been widely adopted by the recreational diving community. Responsibility In professional diving the responsibilities of the participants are distributed according to their role in a project, and may be formally defined by legislation. The client is obliged to divulge any information they are aware of regarding hazards inherent in the site, the work, or the equipment and materials they specify. The contractor is responsible for risk assessment, specifying the mode of diving and safe practices to be followed during the diving operations, and the supervisor is responsible for job safety, following the specified procedures and managing contingencies and incidents. The diver and other members of the dive team are responsible for carrying out the operations according to the prescribed procedures and for notifying the supervisor of any changes in circumstances that could affect team safety. The stand-by diver may be required to assist or rescue the working diver in the event of an emergency. The contracted diving medical practitioner will advise on occupational health issues during the planning, and will be available through live telecommunications to advise on treatment in the event of an injury. As professional service providers, diving instructors and professional dive leaders have a duty of care to their clients and contractual obligations to both the certification agency with which they are registered, and the client, related to the training standards and their terms of registration with the agency. Responsibilities to the client are usually restricted as far as legally possible by terms and conditions of service and waivers required of the client. Recreational divers are generally not members of the agency which issues their certification, and their responsibility for safety is often not specifically different from that of a non-diver citizen or tourist. There are some responsibilities conventionally accepted as applying to the dive buddy in terms of the training standard and recommendations of the certification agency, but the buddy is not legally bound by the standards of the agency, and is not required to put themself at unacceptable risk. There is no clear duty of care between dive buddies. There are a few countries where there are laws specifically relating to recreational diving, such as Israel and the Maldives. Occupational safety