I once did a very dumb thing while duck hunting at Great Bay WMA.
I did start shivering out of control once I was out but dried my self fast, dressed & was good to go. It was a stupid thing to do for sure. But when you're young & dumb you feel invincible.
The fact that you were shivering is good. I've seen first hand. When you stop shivering, not good. I will say this, I've done lake plunges for animal charity, go figure. Lake water or river water like Batsto, blows the heck out of sea water for cold. Whether the salinity, or the movement, the sea seems easier. I though I got in real trouble once doing a lake swim, I cramped up, and yet had to go back in to get a lady out. Lakes or any still cold water is wicked cold!!!
I've been in the Batsto on labor day and froze the nunnies off and swam in Lake Nescochague in October. It will make you mindful trust me.
My real goal is to do one of the major hardcore, thick ice on the lake plunges one day like Guy showed. I must go North. One day after I've safely raised the family and got nuthin' left to loose. My daughter fights hard to go in every year and my wife has stood her ground, citing that dad is a moron. I think it will be soon though.
A few years back I had a chance to break a plunge record with my son Sammy. Two six year olds went in logged as the youngest ever. They were older than him as his birthday is in January, and he just turned six, mere weeks before the plunge. I had it in the bag! I almost... tossed him in just to get the record but, my marriage may have suffered.
g.