Snorkeling Tour

[PrincessTrisha]

We're going to California in November 2008 - I know it will be coldish (right now here it's 13 below celcius with windchill making it feel like -20 celcius so cold is a relative term). But my Dad is really into snorkeling, and since the trip is for his 60th birthday, I'd like to find a tour for him to take. Neither my mom nor I have any interest in going so it would be just him. We will have a car so driving from the Disneyland area won't be a problem.

Can anyone suggest a good, reputable place to book a snorkeling tour from - maybe in the San Diego - La Jolla area?