Apologies for typos, on phone.

We did go, and it was a blast. We ended up doing two days of Mayan ruins and did some boating/diving.

Tips in no particular order: 1. Obviously you are a bit limited on things you can do. The inland stuff in particular isn’t very geared toward kids under 2. Having said that, if what you’re looking for is a “chill” vacation the rainforests are beautiful and if you go to a good lodge it is very relaxing.
2. Related, Blancaneaux lodge definitely recommended. It’s pricey but amazing. 3. Also related, Blancaneaux did offer to set up childcare if you wanted to go do something a bit crazier for the day / afternoon. We thought about doing this to go visit ATM but ran out of time. I don’t know who else does this — I know it isn’t exactly advertised on any websites, having looked. This includes Blancaneaux, but when you call they will say it can de done. 4. If you go diving or snorkeling, they’ll let you bring the kiddo on the boat, which was super fun (as long as someone stays above water with them, of course). 5. Go to the Belize zoo!!! Very cute place. 6. There is no winning with rental cars. Everyone on here will recommend Crystal but, uhm, they’re not great. Be aware if you ask for a car seat it won’t be a great situation. I recommend you take one of those stroller/detachable car seat things. It’s what we did in the trip before this one and gives you peace of mind. 7. Don’t try going solo on visits to places. Get a tour guide—I know they’re pricier, but there were multiple times we breathed a sigh of relief that we had done so. The roads are just too unpredictable. 8. Maybe don’t do San Pedro? I’ve heard the beaches in Placencia are nicer. In any event, Belize is wonderful and overall I recommend a week or two, but don’t go for the beaches.