We went last Sept. and I bought a reloadable underwater film camera to take pix of. I think I shot about 4 rolls of 24 (800 film) I was pretty happy with my pix. Also, while I was doing the dolphin swim with my DD8, I had my DM and DSis take pix and photos from rocks. After the swim they showed us the pix they took but they seemed to be having a problem so we didn't see many-we just left. There was no pressure to buy.
I also used my digital camera to take alot of pix around the park. During rain delay, continental breakfast, dolphin orientation, lunch, and while arriving and leaving the park.
The reloadable camera (Snapsights) I got was $14.95 w/flash (at REI) and is now 16.95. I figured it was cheaper to buy this camera and buy my own film. Plus it has a flash! Next time I will have my pix processed only to a CD and wait to order pix after I've had a chance to edit them. I was able to color correct them and they looked much better.
If I was to go to DC again, I would probably invest in a underwater dig. camera. My sister recently checked on them and found a good one for under $70. When you figure the cost of film it doesn't take long to make up the difference between that camera and those disposibles (or the film for my reloadable one.)
This was taken with Snapsights camera
So was this
DSis took this from the shore with my good digital camera