How to improve surfing skills without water?

Hey guys,
I'm looking for any and all advice on how to become a better surfer without actually being in the water.
In case it sounds like a stupid question, I should explain that I live in a place without surfable waves so I only get to go on surf-trips a few times/months a year. However, I don't want to have to start out from scratch everytime I get to go and stay a beginner forever.
So: How do you improve your surf skills on land? Any particular useful exercises for fitness, balance and is it possible to train other moves than the pop-up on land (or in a pool)? Can you practice turns or even duck-diving somehow?
All advice is appreciated
Nik
I'm looking for any and all advice on how to become a better surfer without actually being in the water.
In case it sounds like a stupid question, I should explain that I live in a place without surfable waves so I only get to go on surf-trips a few times/months a year. However, I don't want to have to start out from scratch everytime I get to go and stay a beginner forever.
So: How do you improve your surf skills on land? Any particular useful exercises for fitness, balance and is it possible to train other moves than the pop-up on land (or in a pool)? Can you practice turns or even duck-diving somehow?
All advice is appreciated

Nik