(It’s from the Fairphone forum, so in case you don’t own a Fairphone just see what you can do regarding removing the battery as well as taking the phone apart, else it has a lot of good general advice regardless of which phone you have. Don’t use rice .)
Turn it off, don’t try to charge it and leave it to dry out for days. It’s a sealed unit so it may take a long time. Take it out of case and perhaps remove sim tray may help.
A good time to make a backup (or check the last existing one) of everything important to you on the phone.
Of course it is regularly a good time to do so .