It is a postcard day in the Whitsundays with a flawless blue sky and turquoise ocean and little wind to speak of.

You flick the starter and open the throttle and ease the jetski out of the marina, keeping it under the speed limit. Then you are out in the water and gun it towards a cruise ship moored in the bay, circle that, then a half-sunken yacht, then tear off again – faster this time – turning, turning, turning, much faster than seems at all safe when you have never done this before; but you are following a guy who knows what he is doing and stick with it.

You hit a wave at an angle and take off, scare yourself and let go the throttle; but you are not supposed to do that and get warned not to do it again. Your job is to keep the throttle open, hang on and trust in the machine, much as you do on a motocross bike.

You are going faster now, gaining confidence. But then the guy you are following pulls a sharp turn and you wind off the throttle, and he is at the other side of the bay. You open it right up to catch him, too focussed to look down at the speedo; but you know – because they said – that you have 130 brake horse power, roughly the same as a 1.9 Audi A4 in a craft which is smaller than a rowing boat. It does 90 knots flat out; or 104 mph, 167 kph.

You slow and stop and edge into a cove at idle speed. The sun-dappled water is perfectly clear and green sea turtles the size of coffee tables swim past so close you could reach down and touch one.

You give the turtles time to get clear, then you turn and you open the throttle again; and you are confident, then, to keep the power on in the turns and leap the waves and trust the jetski to stay afloat; and you want to stay out on the water all afternoon but have only booked for the morning and reluctantly head back to the marina.

(c) Richard Senior 2014