With the Canon WP-DC23 waterproof case for the Canon PowerShot SD770 IS, you can use your digital camera to take underwater shots at depths of up to 130' (40 m). Of course it's also ideal for taking worry-free pictures in the rain, at the beach, or on the ski slopes.
You can use your camera's internal flash for lighting purposes. Or, use the internal flash to trigger a slaved external strobe like those made by Fantasea, Sea & Sea, Ikelite, or Sealife.
Canon WP-DC23 Underwater Housing for Canon PowerShot SD770 IS