[Q] Is the waterproof thing good ? topic

Hi guys,
Firstly, I am sorry if my english is bad, I will make grammatical error please excuse me for that :)

Secondly, here's my question : About the waterproof. Is it good ? I mean I read on other thread that it was not the greatest thing but I want to know more about that, should I avoid full immersion for example ? Or for too much time ? If I can immerse it in water, what should I do to keep it safe ?

Thanks in advance for your answer ! ;)