As long as I know the depth is sufficient; I’ll dive or jump right in.
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They’ll descend after a while. They always have in the past, anyway.
No, my lack of gills makes me unable to breath until I surface. 
That’s why I started jumping in. Soaking my boys was always the hardest part.
Usually walk in until the water gets to the upper thighs, then dive.
IANAD, but I find that’s usually caused by my own testicles retreating so far upwards that they get caught in my throat.
Speaking of the boys, though IANAD, but I find that’s usually caused by my own testicles retreating so far upwards that they get caught in my throat.
Exact same for me. Nothing is worse than slowly dipping your 'nads into chilly water one testicle at a time.
Pool, lake, wherever: Ease in sloooooooowly…
There’s a Calvin and Hobbes about this somewhere. 
I wade in until I get about waist deep (it’s Lake Michigan I’m wading into, diving in from the shore is not feasable**) then just sit down.
I haven’t done it yet this year. The water’s still not in the 40’s yet.
Ditto…nothing like cannon-balling into icy water!
-Mosquito
We’ll never know NOW, will we?!
>Splash!<
I try to get in fast, whenever possible. If not able to dive in, I’ll still go as fast as I can - May as well get it over with as soon as I can.
Usually ease in to waist level , then splash water on face and torso before submerging.
Having done life guard work on Lake Huron, in a section that was an inlet and never seem to warm up until late August, I have done both the dive in and wade in.
Dive in is the only way to go.
If your lungs aren’t full the first thing that happens when you enter cold water is that you refexively gasp. Many people who fall into very cold water drown immediately due to this reflex.
When I was a competitive swimmer in Canberra I was racing early one morning at the start of the season. It was really cold and no-one had a pre race swim. When we dived in nearly everyone in the race floundered through one or two strokes and then headed for the side of the pool. I remember it took a huge effort to get enough breath to make it out of the pool. I don’t think I could have swum a lap if my life depended on it.
What do you consider cold water…I mean, other than ice floes in the vicinity?
Olympic swimming regulations say the pool temperature should be 80 degrees. I have a pool and trust me, I ain’t going in when it is only 80 unless you push me.
Ideal temp is about 84 to 86.
I always watch those fools in the Polar Bear clubs in January diving into frozen rivers and wonder…why!!!
Ease in until the water is just below butt-level, then dunk all the way in.
How do I enter cold water?
Danger! Danger! Does not compute!
If it isn’t bathtub temperature, I ain’t getting in.
Well, yes. That is what I consider cold water. I paddle when the rivers are just breaking up, and I fish people out of that stuff.
If they are dressed properly (dry suit or wet suit), and upon imersion keep their mouts shut and face and font of neck protected when they first go in, they usually will be able to swim for quite a while, making rescue a lot easier since they can swim and hang on to your rope or boat).
If a person has their mouth open and gets a shot of very cold water in it upon going in, in combination with the face and front of the neck being immersed at the same time, there is a good chance that the person will seize up for a minute or so, which can be very scary for the person, and can delay rescue. In rare instances (I have only come across it once), the seizing up may include the heart stopping.
If a person is not dressed properly, then even if they keep their mouth shut they will probably seize up. What is worse is that they will cool off so quickly that even if they recover from the initial seizing up, they will loose muscle control in a couple of minutes, again making rescue difficult, and if severe enough, risking heart failure during rewarming.
If you are interested in this sort of thing, dig about on “mamalian dive reflex” (seizing up from the initial dunking), and “hypothermia” (the body cooling down and losing muscle control and then losing consciousness).
Dive right in, or, if it’s at a beach where diving isn’t feasible, ease in until the water’s at about mid-thigh and drop down to neck-level. It usually isn’t long before I get acclimatized to the water temperature, and I’d rather get the adjustment period started as soon as possible.
CJ