My toe nail is almost totally loose. When will it fall of?

It is the nail of my big toe.
It is not a healthy nail, for some fifteen years already, it being very hard, thick and un-even.
Now, since some weeks (i noticed that i swum much in sea water for about three weeks), the nail is disconnected from the bed(?) and it is only attached to the…., you know, where they start growing from.
Does anybody have experience with falling of of nails?
Will it go by itself, or can i help it fall of?
Not my nail