DiveLikeAMuppet
Contributor
This. It’s not magic, you could just ask some friends to go dive in a lake with you few times. There are only few skills to learn, it honestly doesn’t matter where you do the course.I bought the PADI drysuit book, and hired the drysuit video from the dive shop, not too far around the corner
Drysuit Diver – Dive RAID International
diveraid.com
And went diving!
You see if you dive in the ocean, it will throw you around covering up your mistakes until you don't make any
If you are doing the course in an ill-fitting rental, I would do it in Mexico - you will cold wet and miserable in leaky rental in cold water. If it’s your own drysuit, I would go for cold water.
Everything else is about comfort and managing a gas bubble which might take few dives - especially if you need to hold an ascent speed. Mexico will feel easy as the undergarment will be thin. Cold water diving will take you some time to adjust - bigger gas bubble, less dexterity and more layers that can feel claustrophobic.
