Camera's memory is empty of previous shots.
            
               
                     
                         Made setting adjustments you will want:-
                         - selected 'white balance = underwater'
- ISO 200 (or a bit higher)
- shutter speed or aperture priority
- (priority shutter speed 200 for me)
 
                    
                
         
        		Flash 'off' or if 'on' and popped 'up'.
              	External diffuser attached.
              	Underwater housing interior is dry.
       			Housing lens clean.
            	O-ring is clean, sitting snugly and greased.
             	Camera in housing.
           		No straps etc. in housing door/ properly closed.
             	Filter (if internal), - is clean and in the housing.
			
         
            
				Silica gel is in the housing.
                Done a dunk test in a small amount of freshwater.
                   
                        Currents - already asked the dive centre
                        Observed other snorkellers to see in which direction they are swimming, 
                        how fast they seem to be 
                        going.   Any signs of rips or currents?
                    
                Sorted out your dive buddy? (see below).
       		
            
 
     
                        
         
       	 
                Seen people come ashore then jump about with their head to one side, trying to unblock their 
                ears?   Entertains the landlubbers.
            
                'Earol Swim' - prevents swimmers' ears - it does.   It's natural.   Just contains olive oil so 
                no harm.   One squirt in each ear. 
            
            
            	
                	Earol natural olive oil
                 
            	 
   			
             
            
           	   
                	Goggles/ mask   ensure lens is clean and spray with anti-fog (or use spittle).
               
            	
       		
             
            
       
                    
    
                        
         								
            
            
            	Covering - don T-shirt (be careful as when wet offers virtually no sun protection), thin neoprene 
                vest is better.
                
                Waterproof sunscreen on all exposed parts.   Especially on back of neck, head (or wear a cap,) 
                back of legs - really important - and arms.   Also on your back if only wearing a T-shirt!
                
                The more covered - less sunscreen, fewer scratches and more warmth retention so a thin neoprene vest makes sense.
   			
            
         
            	   Got your buddies sorted?
                
                For safety,  two people is officially sub-optimal and three the minimum.   Apparently, technically, 
                one should be on shore watching the pair.   Of the pair in the water, one is meant to stay on top 
                and watch while the other dives.   Then obviously the roles are swapped so the other one dives.
      			
   			 Some of us have  trouble getting a buddy interested in the photography aspect.   So, do your best to be safe.