sentences:  Underwater diving interventions, particularly on scuba, provide the capacity for scientists to make direct observations on site and in real time, which allow for ground-truthing of larger scale observations and occasional serendipitous observations outside the planned experiment.Human dexterity remains less expensive and more adaptable to unexpected complexities in experimental setup than remotely operated and robotic alternatives in the shallower depth ranges.Scuba has also provided insights which would be unlikely to occur without direct observation, where hypotheses produced by deductive reasoning have not predicted interactive and behavioural characteristics of marine organisms, and these would not be likely to be detected from remote sensing or video or other methods which do not provide the full context and detail available to the diver.