sentences:  The Research Diving Unit of the University of Cape Town has specialised in training divers to Class 3, 4 and 5 for scientific work continuously since the mid 20th century, and is the university's in-house diving contractor.As diving is an activity that is considered to put the diver at a higher than normal risk to health, in the UK all diving at work, including scientific diving, is regulated through the Diving at Work Regulations, 1997 and the associated approved codes of practice, which are implemented by the Health and Safety Executive.The code of practice for scientific diving also covers archaeological diving and diving in public aquariums.