Cave diving is the exploration of submerged natural overhead environments beyond sight of daylight. For those who possess the highly specialized training, equipment and skills required, it can be a very rewarding experience. It can also be deceptively easy and extremely dangerous — especially for those who lack the prerequisite knowledge, equipment and skills.
Technical diving is a term used to describe all diving methods that exceed the limits imposed on depth and/or immersion time for recreational scuba diving. Technical diving often involves the use of special gas mixtures (rather than compressed air) for breathing. The type of gas mixture used is determined either by the maximum depth planned for the dive or by the length of time that the diver intends to spend underwater. While the recommended maximum depth for conventional scuba diving is 130 feet, technical divers may work in the range of 170 feet to 350 feet, sometimes even deeper.
Technical diving resources
Equivalent Ratings with Other Scuba Diving Agencies
Advanced Diver Magazine