Pool is warm.
The pool is expensive.
I only get an hour at a time - just enough time to get to the stage of making progress - then I have to stop.
I don't have to wear endless layers of restricting warm gear.
It provides less buoyancy.
It's not the sea.
The sea is cold.
The sea is free.
I only manage to practice for about an hour before I get so cold I can't concentrate
(and yes! I can get my hood over the top of my tuilik).
I have to wear layers of movement restricting gear.
It provides lots of buoyancy.
It's the sea.
Either way an hour is about all I can afford.