I have read a few sad threads regarding a drone crash into water and I have never seen this mentioned Distilled Water Cleaning.
As a boffin I was taught this method many years ago (when I used to hand solder military electronic equipment) for removing water soluble soldering flux/residue. It worked well

Distilled water is non-conductive, it is the dissolved salts that make lake and sea water conductive. Apart from corrosion, the conductivity means that electrical circuits may suffer damage from electric currents passing through the water.

Total drying of any components still takes a while in a warm and dry environment (dessicant helps), but by flushing and gently scrubbing away any contamination immediately after a dunking with distilled water there is a chance to minimise further damage.

I am not prepared to dunk my Mavic Pro to test this theory btw, but just thought that I might mention it as a possible solution for people who manage to test the swimming abilities of their DJI drone and manage to rescue it quickly

The first thing to suffer appears to be the battery pack, so after removing it immediately, write it off and replace it but if you get lucky your biggest problem might be water in the camera lens.

Sadly, your logic does not hold water. Pun intended.
The water may be 'pure' up until the moment it is in contact with soluble substances, including metal itself. I know your objective is to dissolve and flush away corrosive salts, and that makes sense. However, water is not good at penetrating small cracks or gaps due to surface tension. You know surface tension, don't you? Where water forms droplets or a distinct border at the edge of the water. The salts left over from dunking love these crevices and will remain active , absorbing atmospheric moisture to continue its silent, destructive action. The worst areas are where you have wound cores and dissimilar metals. Loads of cracks to hide in.
If the electronics belong to something that is not going to fall out of the sky, like a camera or laptop, then fine, it is worth the risk. It is irresponsible to fly something that has a known defect.
Regarding the use of desiccants. Rice and silica gel, will absorb moisture to a degree, however, unless you seal the stuff in a bag, the infinite amount of moisture in the air will quickly saturate it. Don't waste your time with desiccants except for storage of dry equipment. Just rely on warm air passing over the damp equipment. That is how evaporation works. Why else would washing on a line dry?  

Hello and good day Boffin. Thank you for reaching out and for the information you have shared with us today. Just a friendly reminder that the DJI Drones are not waterproof. In addition operating the said drone in water can damage the drone itself. Thank you.

Interesting, never was taught to use Distilled water for cleaning when doing solder repairs.  Instead we were instructed to use special cleaning fluid to dissolve and clean blue & sticky liquid flux and residue of, from circuit boards.

Have used Distilled water to clean keyboards doused with sugar & cream laden coffee, soda pop, and on one occasion a beer spill at work.  (Not my keyboard or beer.).  When possible, flush Distilled water out with special cleaning fluid.

HedgeTrimmer Posted at 5-18 11:56
Interesting, never was taught to use Distilled water for cleaning when doing solder repairs.  Instead we were instructed to use special cleaning fluid to dissolve and clean blue & sticky liquid flux and residue of, from circuit boards.

Have used Distilled water to clean keyboards doused with sugar & cream laden coffee, soda pop, and on one occasion a beer spill at work.  (Not my keyboard or beer.).  When possible, flush Distilled water out with special cleaning fluid.

Why I mentioned it was that if the drone is already wet from a dunking then rinsing with distilled water before drying would be preferable to attempting to dry it with lake or sea water remaining in the hardware

Boffin Posted at 5-18 15:37
Why I mentioned it was that if the drone is already wet from a dunking then rinsing with distilled water before drying would be preferable to attempting to dry it with lake or sea water remaining in the hardware

Agreed.  

Dunking drone in distilled water to rinse off lake, pond, stream water isn't going to hurt.  Doing same for ocean water can only help.