Article continues below advertisementBritney Spears is having a ball on vacation, but some of the social media posts she shared while on her trip have fans concerned for her well-being.A few days after she defended herself for posting a naked photo, the singer uploaded a video where she flaunted her fit figure while aboard a boat.Article continues below advertisementBritney Spears' Boat DaySource: @britneyspears/instagramBritney Spears rocked a swimsuit with cut-outs while aboard a boat.