Whats the policy on bringing your own soda on board?

You might be able to call the cruise line directly to check. If you share which cruise line, we may be able to give better advice Royal Caribbean's website has their policy at https://www.royalcaribbean.com/faq/questions/food-drink-onboard-policy It states, "Guests may also bring non-alcoholic beverages as carry-on items on boarding day. Non-alcoholic beverages may not exceed 12 standard (17 oz.) cans, bottles or cartons per stateroom. Milk and distilled water brought on for infant, medical, or dietary use are permitted. "

we always bring a 12 pack of cans. bottles seem to get more scrutiny, maybe cause they could be refilled? i'd switch to cans if you can. we put them in a small rolling cooler bag and carry it on, never check it. one thing nobody mentions—if you're carrying it in a backpack, take it out at the scanner like you would a laptop. they flagged ours once cause it was a dense block and they wanted to see inside. now we just put the cans loose in the top of the bag so the x-ray is obvious. saved us a bag search last time. also, check if your line has that "sealed" requirement. some say it has to be factory sealed, which your bottles are, but we've seen them shake cans to listen for liquid. weird, but it happens. which line are you on? might be able to give a more specific heads-up.