Carey’s 5-year-old twins, Monroe and Moroccan, who she shares with estranged husband Nick Cannon, joined the singer and the son of late media tycoon Kerry Packer for the celebrations.
The songstress shared a series of snaps to Instagram while on board the yacht, writing alongside an image of her and Packer, “Happy 4th of July. Thank you for the #fireworks darling.”
Earlier in the day, Carey also posted a tribute to her late father on the 14th anniversary of his death. “Happy Independence Day RIP Alfred Roy Carey,” she wrote alongside a selfie of her holding a bunch of sunflowers.
Carey and Packer also posed with Hollywood heavyweight David Geffen, whose yacht, the Rising Sun, they had been on earlier in the day.
Packer, who is estimated by Forbes to be worth $US3.9 billion, popped the question to Carey in December after dating for less than a year. He presented the US singer with a diamond ring estimated to be valued at $A11 million.