Going to villa with a pool and my 21 month old is fearless in water (we live in a swimming pool so she goes most days) and loves to run up the side and jump in.
So far we've avoided flotation aids but I think it would be good to get something -- even though we will supervise her at all times. It's just not having been there you don't know the lie of the land.
Life jacket, or buoyancy suit and arm bands? Or all three (and see which she hates the least?)