Mariah Carey is about to launch the third leg of her epic "Number 1's" residency in Las Vegas on Feb. 2, but first, some fun in the sun!

The singer was spotted in St. Barts over the weekend, looking fit and fabulous as she enjoyed a walk on the beach in a Louis Vuitton bikini, sun hat, and snakeskin-print sarong.

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A source tells ET the 45-year-old diva is staying on billionaire boyfriend James Packer’s yacht, the Arctic P. She is vacationing with her 4-year-old twins, Monroe and Moroccan -- who have been enjoying parties on the beach -- along with a crew of babysitters and hairdressers.

Carey posted a pic from her tropical getaway on Instagram on Sunday, sharing a shot of “#dinneratthebeach.” 

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The singer revealed how she and Packer first hit it off in an interview with Steve Harvey back in November.

"We first met in Aspen," she explained. "We were at the 'Hercules' premiere. We were talking and laughing and people were getting mad at us and stuff like that. So we hit it off."

WATCH: Mariah Carey Reveals How She Met Billionaire Boyfriend James Packer and Shows Off Stunning New Jewels