Depending on where you are staying, this might not be an optin, but my now 4 and 6 year old grandsons have to go to Rojo Lounge at Azul for the hermit crab migration. The food is excellent there as well, so it was no sacrifice. Their lobster pizza is excellent. Depending on when you come in July, you might be timing it right. There is also the zoo on the mainland. Mainly my grandsons just want to swim and explore. This summer will be their third trip and they keep telling their mom that they are moving to Belize. We stay north so I can't tell you what there is to do in town for the younger kids. At night you will find me with my head gear (flashlight) walking the beach and the docks looking for all the interesting "live" nightlife for hours.