Dry snorkels sound excellent, and generally are, but kow about the position of the snorkel tube.
  				
		  		When you are swimming along -
		  		head down - your snorkel tube is straight up 
		  		- at 12 o'clock.
  					
  
                  
          
    		
	 	 
        
    	
                But, when you come up from a dive, 
                head up, your snorkel tube is level with the water - (3 o'clock). or 
          		If you put your mouth slightly up, 
            	the tube can be pointing slightly downwards - (4 o'clock') with the valve beneath the surface.
   		  
            
      			
                
        	
    	 
    
    	
                    So, you try to draw a breathe in and 
                    the upper valve is closed 
                    and you panic a bit.
                    
                    The snorkel is doing exactly what it is meant to.
                    
                    As long as you understand what is happening, 
                    dry snorkels work very well.
                    
                    Oceanic Ultradry is the one I use
                    but there is quite a range now
                    so ask your dive shop.