We did this once. Now others have had agood time and I had an OK time.
The boat was dirty, but the narration was excellant and I learned alot. it was very choppy so we didnt get tot see the ship wreck. Once we got to the shop where we could go down stairs and look, the stairs were steep and tricky. I felt sorry for parents with little kids.
I saw 7 or 8 small fish and one sand dollar. I was disappointed. Now it may not be that way all the time, but for our cruise it was. Around the glass bottom there was a wooden wall and people with young kids did have to hold them up to see. For us it was fine but short kids had a little trouble.
There was free punch, but the glass container was so filthy looking I didnt take any punch.
For me, if I wanted to see fish I would go to Atlantis to see the Dig. It is a great aquarium. The tour moves fast, but after it is over you can go back through as many times as you want, at your own pace. Just keep your wrist band on to prove you paid for it.
Of course for your cruise there may be lots of fish? Fish do travel all the time.
It was 3 years ago when we took this excursion, hopefully someone who has been on it recently will be able to tell you if it is cleaner and if they saw anything.
Another thing at Nassau your kids may enjoy is irght at the port there is a horse and carriage ride. It takes about 20 to 25 minutes, cost $10 per person, tip if you want. It is narrated by the driver and you drive through town. Easy for younger kids to do. No reservation, just walk over and do it. Very nice people there.
also a great pirate museum for $12 per person, takes about an hour to do, kids seem to like that too.2 blocks behind the straw market.
Good luck,
mom x4,grandma x4