sentences:  Technological advances have made it possible for scientific divers to accomplish more on a dive, but they have also increased the complexity and the task loading of both the diving equipment and the work done, and consequently require higher levels of trainng and preparation to safely and effectively use this technology.It is preferable for effective learning and safety that such specialisation training is done systematically and under controlled conditions, rather than on site and on the job.Environmental conditions for training should include exercises in conditions as close as reasonably practicable to field conditions.