That was a bit misleading then.
Turning on the phone which is not dry can cause further damage. I understand that on a trip it might be difficult not to use a phone ( I killed one of my previous phones this way), but if only possible
From the forum waterwiki
"Once you are in a safe and dry place disassemble the phone as far as you can - so in the case of the FP2/FP3/FP4/FP5 that means at take out each individual module (…)
Let it dry for days
As important as it is to turn the phone off quickly it’s just as important to not “test” it until it’s super dry.
Check for damage (still before turning on)
Check each part of the phone for signs of damage. Especially check the connectors to see if there is some sediment on it. This can come from the minerals in the water. Carefully clean it off with distilled water or alcohol."