How to fill up sinuses with seawater?

[dimitris33]

Before dives, in order to flush out all mucus.

Do I have to put my head into water and inhale through the nose or is there any other proper way? And how to reach the frontal sinus too?

Any tips or position?

In the assumption of course that the water is clear.

 

[Don Paul]

I just snort it after I dip my mask, I then tilt my head side to side and back to front. I do it a few times followed my bending at the waist and putting my hands flat on the deck. This gets the seawater into the top of my sinuses.
Some guys use saline in a plastic squeeze bottle.
I left out the part about ejecting the waste water back into the sea.
I'm having breakfast.
Cheers, Don
PS here's another way in Spanish.