Crawford and her husband, Rande Gerber, are currently soaking up the sun on the Caribbean island, where Gerber swept his wife away on his Casamigos Tequila private jet.
"@RandeGerber whisking me away for my birthday weekend!" Crawford Instagrammed on Wednesday.
According to an eyewitness, the two couldn't look more in love on their vacay, even after being married for 17 years.
"They are a great couple -- holding hands, looking into each other's eyes, very happy and loved up," the eyewitness tells ET. "Rande is always such a gentleman with her, making sure she is always OK."
Not surprisingly, Crawford's been reflecting on her upcoming milestone birthday. On Thursday, she posted this cute throwback photo of herself blowing out the candles on her epic Vogue-themed cake for her 21st birthday.
"#TBT My 21st birthday. The cake says 'What's Next?' -- now I know!" she wrote.