Welcome back, Corlis! Both of these underwater submarine adventures offer beautiful views of life under the sea. I have only taken the Semi-Sub adventure, but if price is a consideration, I can assure you that if you do decide on this adventure (over the dolphin swim you asked about in your previous question), you will certainly see just as many fish and reefs as you would if you take the fully submersed submarine adventure. The Semi-Sub goes to the shallow water reefs, so when you climb down below, you're very close to the ocean floor under the water, just as you would be with the fully submersed sub, though that would be in deeper water.
I do like that this
Seaworld Observer Semi-Sub adventure also includes a visit to a sunken ship wreck, which makes for a different viewing experience. Plus, we loved when a diver on the boat hopped in to feed the fish near our windows. It drew more fish close for us to see!
I'm sure the
Atlantis Submarine Expedition is wonderful too, but if your boys aren't so concerned with the boat actually being fully submersed, I'd probably opt for the Semi-Sub just for the price and fact that I know it offers beautiful views too.
You did ask about educational value in your previous question, so let me address that a bit more here. My kids did learn about fish and reefs on this adventure, though not in the hands-on way they did in the dolphin adventure. I remember pictures above the windows of our semi-sub and laminated cards we could hold that showed the different fish we may spot. That gave them an activity to try to figure out which fish was which when we spotted them. And the guide was very informative too.
I hope that gives you a better insight into these adventures, Corlis!
Marcy