If you can see it, it can affect you. That's a good rule of thumb. I have read that lightning can affect an area 60 feet from the strike, but on the water I'm sure that would be more since water is a conductor. However, if you can see lightening then you are close enough to get hit. One bolt may be a mile or two away, but the next could be the last thing you ever see. Like my friend says, that's when you say "oh" on earth, and "sh--" in heaven.

Electric shocks can cause muscles to contract uncontrollably. You could easily drown even if you didn't get hit hard and just got a jolt from a nearby strike.