Welcome back, Christy! There are so many fabulous Port Adventures for everyone in the family to enjoy when you arrive in Nassau in the Bahamas.
When you select Nassau from right side drop down box on the
Port Adventures menu, you'll see the full listing of adventures available there. Scroll down, watching the left hand side of your screen where you'll see a listing of ages. Click on ages 3-4. This will narrow down the Port Adventures to only those in that port on which your three-year old can join you.
Out of these, I can highly recommend a few! If you'd like to visit Atlantis, the Atlantis Beach Day and Discover Atlantis adventure is great for the whole family. There's also a different version of this that doesn't include time at the Atlantis beach, called Discover Atlantis. What I like about these two adventures, besides the time exploring this beautiful resort, is that there are multiple return times back to the ship, so you can stay as short or as long as you'd like, or your older son can stay longer with one parent while the other returns early with the little one. It's a nice perk!
I also highly recommend swimming with the dolphins at Blue Lagoon. My daughter had the time of her life when we did this, as she is absolutely in love with dolphins, so the chance to see them up close and interact with them was priceless for her! Plus, we got to stay and enjoy Blue Lagoon Beach for the rest of the day afterwards since we chose the earliest swim time! If you'd prefer to simply enjoy the beach and not swim with the dolphins, you can just book the Blue Lagoon Island Beach Day. It's a beautiful island to explore!
Finally, we really enjoyed our trip on a SeaWorld Semi-Submarine viewing the fish underwater. Your kids are at a great age for this adventure too!
Have fun planning, Christy!