Cruising with a 5 month old??

[Michigan RN]

My family booked a cruise for 6-03, kids are 16-16-14-9. We've been trying to have another baby and wonder if we should take him/her with us at such a young age. We are possibly looking at a 5-6 month old. Would it be too hot? We are also staing at Beach club 5 nights prior to the cruise. Would it make it not as enjoyable to be with the older ones? I don't know if I could leave the baby back home, even if it's with grandma. Any suggestions would help!!