Nice Mike, it reminds me of a glass bowl! Sorry, no sea cows on this trip...just missed them. I've found most water to be very reflective when it comes to IR so no, I would say the IR rays don't penetrate very deep. You can see in this photo that you can see just below the surface, but a foot or so down it become impenetrable. @Tom, the R72 filters are resonable ($30 eBay), and the favorite of most people because they let a little normal light reach the sensor, thus allowing you to set your white balance and play with some false color schemes. It depends a lot on the camera though. My most recent image have been taken with a Wratten 87 filter, and they are more costly, ...though you can approximate their effect using unexposed slide film, though the optics are questionable.

Kort Kramer - Kramer Kreations