Energy system interplay
During surfing the surfer starts off using their aerobic system, when carrying their board into the water wouldn't need any high intensity. Their heart rate would be at 70-85% Then as they paddle their board out to the waves they are then doing a high intensity activity, doing this would make them go into an anaerobic system because it is a high intensity activity with the max heart rate reaching 85-95% and also it is a long duration activity. Then as they do get a wave, they would have a burst of the ATP/PC system because they are doing a quick action to get up onto the board.
Local Style - Surfing Uluwatu, Bali - Ep 1
Usain Bolt wins 200 meter sprint
Hungary vs Australia - Women's Water Polo - Beijing 2008 Summer Olympic Games
When playing water polo you would be working anaerobically because it is a high level of intensity and it is a long duration sport. Although when the player passes the ball or goes for a goal they use their ATP/PC system, due to it being a quick burst of ATP.