I can't think of anything I enjoy about the island that would be good for a five year old. Hanging out at the hotel by the pool and a bus tour are the only baby safe/centered activities I can imagine. Diving, snorkeling, driving jeeps around the island and excellent restaurants are the highlights of the island to me.
Beach and pool, time with Mama, Daddy and grandparents - what more could a baby want?!
We're going to try the butterfly garden this year, but we have an older toddler as well as a baby. Within reason, a baby that small will do whatever you do. Obviously all of the adults can't go snorkling/diving all at once with the baby, but we find plenty to keep us busy without snorkling or diving.
Baby Beach -just to be lazy and float on my raft and snorkle too
We did everything we normally do just modified it. Less time in the direct hot sun. More shade. Naps in the shade under the stroller shade. Took turns snorkeling and while one stayed back with the baby in the water. Ate dinner early in the evening or late with baby sleeping in car seat/carrier. Ate out. Traveled the island. Went to the beach, pool, aerobics, etc.
Made more memories and had a blast.
Baby Beach there's a breakwater no waves 2" to start, take turns to snorkel where the water changes color, plenty of fish & if you take bagels & sprinkle in the water knee deep they will come to you & your baby great first pic's with and the fishies.