How are you? We recently went for a mini trip to Goa. Since I am Goan, and I stay near beach I did not carry lot of things to the beach. So below I mentioned the absolute necessary things to carry while going to the beach with a 9 month old baby.
9 month old baby are usually able to sit on their own and is an absolute right time for the babies to get introduced with beach water. Else, it is difficult for them to get used to water eventually. We took Aruhi to beach on three consecutive days and she loved water. So below is the list of things to carry in your diaper bag.
Cloths 2-3 sets of cloths
Wear a tee and shorts and not single dress for girls
Avoid frills dress Wear comfortable clothes for kid Preferably wear half pant for baby
Keep extra diapers. Wear diaper and take in water. And once out from water, immediately remove the diaper as it would be too heavy.
No need to carry beach set. Beach set can be taken once baby is more than 15 months and able to play on his own. Babies tend to put everything in mouth at this age, and its risky if sand enters the body.
Pair of socks. Do not wear socks in water.
Towel Blanket to wrap once baby is out from water.
Warm blanket for extra warmth Empty polyethene bag for carrying wet cloths Plastic mat for changing cloth. You don't want sand again to enter the body and bag.
Oil/rash cream/lotion as skin gets too dry in water.
Cap after the baby is out from water.
The above mentioned things are must because usually its windy near beaches and baby can catch cold. So be safe, as soon as the baby is out, wipe the body, change the cloths and wrap in towel and wear a cap.
If you have any queries, please feel free to ask in comments. I will try my best to answer the same ASAP. Also I would suggest travel for an experience which you can cherish forever.