Yes, I've had several people suggest the Sigma 17-70. However, I have also heard that support for this lens on a D200 in a Subal housing is difficult. Specifically, the newer versions (OS, HSM) are too big to put a gear on. I'm looking for an older version (non OS, HSM), but have been striking out so far. The older ones that I have found don't specifically say they can be mounted to a Nikon camera body.
Has anyone else had this problem?
I use the Sigma 17-70 with my D300 in a Subal housing and here's how I handled it:
I checked out the typical places to buy used lenses (e.g. KEH, Adorama, Fred Miranda, etc) and finally got lucky when I found a NON-HSM Sigma 17-70 lens at Adorama for much less than the HSM version. I then was able to buy a zoom gear for it at Reef Photo which allowed me to change the focal length underwater. I think if you check out the places that sell used lenses (yes, even the big auction site as well as the ones I mentioned above) you will eventually find one that can be mounted on your D200. You might also give Reef Photo (right in your backyard), one of our sponsors, a call to see if they have the zoom gear for the lens. I would also check with Backscatter, another sponsor, to see if they have the zoom gear.
It may take some effort on part, but it's effort that should eventually be successful in finding what you want.
Ellen