I have got a puncture in my airbed but cannot seem to find the hole. Can you tell me if there is an easy, surefire way of finding the puncture?

I'm not sure about air beds but with tyres you spray water on them and see if there are any places where the water bubbles.

Alternatively you could hold some talcum powder in the palm of your hand and slowly move along the whole bed.. if the powder blows away then you have your hole!

Apply some pressure to the bed with both these methods and best to do it outside :)