I was filming my freind water skiing flying the drone side ways (I know not advisable) and hit a tree and my mavic fell into the freshwater lake.  I found the mavic sitting under water about 2 feet deep, after about 20 minutes of searching, I took battery off and I am now waiting for it to dry out.  24 hours has passed now, dare I switch it on again !!

If you have DJI Refresh then I would just submit a claim and not screw around with the "drying out" process.

There are two schools of thought. The more common seems to be that you should rinse it thoroughly with distilled water, seal it in a container with rice (silica gel desiccant is a better choice) for a couple of days to draw out the moisture, and then see if it'll fly.

The problem is that water can damage electronics in subtle ways that don't show up immediately, so the other line of thought is that you should treat it as a total loss and never consider it safe to fly again.

Ultimately it's your choice, though from what I've seen the success rate for bringing "drowned" Mavics back to life is fairly low, and DJI won't even attempt a repair when it receives one that's been submerged.

We feel so sorry for the accident you have with the drone. And we do not suggest to use or repair watered drone. Did you buy DJI Care Refresh? If yes, we recommend you to contact our Support Team via support.eu@dji.com to refresh with a small additional cost.

Do not switch it on - residual moisture on fine electric circuitry will increase yr risk of short circuit. If you have care refresh - send it back and pay the bit extra and start again. if no care refresh then do yr best to dry it. Forbid it happens to me but if it did i would open the drone as much as i could and try to dry it out as much as possible with hairdryer and then stick it in a bag full of rice or silica for at least a week before attempting to switch on again. Not saying this will work just what i would try if i had nothing to lose and everything to gain  - good luck

Did you rinse with distilled water? If not do this.  Otherwise, the dissolved solids will likely cause corrosion and/or direct shorts when the water dries out.