Hello fiona
I haven’t been diving in Cuba but I tried it in Egypt and my children loved it…they were a little older though... Diving can be dangerous not only for kids but while searching the net I came across this site
http://www.captivatingcuba.com/recommended.php?id=4
which says that many Cuban hotels offer basic diving courses for beginners, so that may be worth looking into
Let me know how it was when you come back…I might go diving in Cuba next year if it’s as good as Egypt was!
Have a lovely holiday in Cuba… or wherever you decide on!
roselllana