The light you'll want will depend on your viz. We're working in 5-10 foot of viz (sometimes less) so a high-powered light with 8 C cell batteries is essential. UK or Princeton Tec make some. I use the UK Light Cannon HID.
If you're just looking in holes during the day, you might want something smaller that's easy to carry around, and that maybe you can just clip to a float or belt when it's not being used.
Well both options day forme and nigth for the friend, thanks:).
Bward and Lunker: thanks for your opinions.