Usually you cannot refresh spells/skills in cf but water breathing is an exception to that rule. So you can eat a new seaweed when you have 1-2 ticks left to refresh the timer.

Maybe you already knew that but then it is a tip for someone else that reads this

And every time one of my characters starts gasping for air, I find myself panicking.

eat seeewed

eat saweed

eat eaweed


And in one of my more embarrassing deaths:

eat seaweed

<prompt>
You are too full.

>Few questions about it....
>
>1) How long does one can stay underwater without 'underwater
>breathing' before drowning?

Not sure. Probably not long enough to do any significant exploration. Luckily seaweed is free, plentiful, and even allowed in Battle.

>2) Do we get a message from the server telling us we're about
>to drown? (I've seen the message 'You are no longer able to
>breath underwater' but I didnt want to die to test how long we
>can hold so I ate another 'waterbreathing' item before the
>hour was gone....)

Yep. You'll get a couple echoes before you die. I don't remember them exactly, but they're rather poignant as to what's going on and to the fact that you're about to die an awful death.

>3) After constant failures attempting to cast 'Cloud of wasp'
>underwater I conclude it doesn't work underwater. I'm I
>wrong?

Bees don't swim. (Remember that when you're fighting a ranger, not just fighting AS a ranger.)