What do "they" think of open water swimming?

Signed up for my first long swim and after hearing the reaction from family and friends (haven't told anyone at work yet), I'm wondering how other people respond when you tell them that you're going to do a swim. Here's some of what I got: "Why on earth would you want to do something like that?" "You're nuts!" "You could drown!" "That's so dangerous!" "You'd better get your will done first." "What are you thinking? You have a family!" "You could get eaten by a shark..." "The jellyfish will get you..." "People invented boats and bridges to get across rivers, we're not supposed to swim across them." "Are you going to use a gas mask?" "The water's so polluted, you are going to get sick." "If you want to swim, can't you do it in the pool where it's safe?" Only one person said "That's awesome, you must be in great shape." Do you get similar responses? And how do you answer them? I'm beginning to wonder what the rest of the world thinks of us...