I did a quick import into Photoshop Elements 2 and did an auto color correction. This is the result:



In regular Photoshop, I would suppose you could either use the curves tool and tone down the blue, or do a similar feat using Levels. That's something I've never been really good at.

Also, to help prevent having to do such activities on the computer, you might see if your camera offers a manual white balance option. Though underwater, there might not be much available to set the white balance with (usually use a grey or white object). Alternatively, you could try selecting either "Shade" or "Cloudy" white balance and see if that warms things up a bit.