Well if you have ever wondered what the pool area's look like when the ship is sailing on undulating waters, then just have a look at the video, this may even be tame? as I'm sure some of you regular cruiser's could tell me, if you have a tale...please share it with me.

Did you know that most Cruise lines fill their pool's with salt water, which now I've said it, it sounds so obvious! The pool is emptied out at night and a fresh batch (fish not included) is pumped back into the pool while everyone is still sleeping, now how do the not catch one fish, it's filtered!

There are exceptions like Princess Cruise's they like to use fresh water unless you consider distilled sea water not to be fresh. Many ships use this process rather than the filtration process to which you refer. It's about as pure as fresh water can possibly be.