Water Shots
One word of advice: do not underestimate the wave's power; begin swimming out with flat water, working your way up to larger waves. You need a custom made camera housing with possibly a flash to fill in the shadows. Lens lengths ranges from super wide to medium telephoto (20mm. to135mm.) shutter speeds 1/500 sec to 1/1000sec. Unless you'd want to experiment with "pannings" at speeds as slow as 1/8 sec. Use a camera light and with a reasonably fast motor drive; I use at present time the Nikon N90x , ( in USA N90s ), which is a great compromise between weight and motor drive speed, having a fast enough autofocus !