The island was awesome. Beautiful, kind and helpful staff. Food was great. Drinks are watered down and AWFUL.
Take a ferry, get there a little slower...but dry and happy.
My kids both hated this excursion and were in tears by the time we got to the shore.
We did the Ziplining and Cave excursion. It was fun, but really hot and we were the last bus to tender back to the boat.
Belize City is not what you'd expect, and the area is unsafe and not somewhere I'd walk around - with or without kids.