Jared Goff's Fiancée, Christen Harper, Kicks Off Bachelorette Party W/ Bikini Bash

Jared Goff's swimsuit model fiancée, Christen Harper, is celebrating her final days as an unmarried woman in fitting fashion ... soaking in the Mexico sun with other models in teeny bikinis!!!

The 30-year-old -- who got engaged to Goff back in June 2023 -- piled into a plane on Thursday morning with a grip of her closest friends ... and headed off to Cabo San Lucas to let loose one last time before her upcoming nuptials.

And, once they touched down, first order of business appeared to be to throw on some swimwear and catch some rays by a pool at a luxurious resort.

Of course, Harper -- who's been featured in Sports Illustrated several times -- was surrounded by other beautiful women who are no stranger to posing in barely-there attire ... including Katie Austin and Elizabeth Turner.

All of the girls seemed to be having a blast ... there were balloons, catered food -- and even temporary tattoos with Goff's mug on them!!

Harper and the ladies then threw on some dresses for a night on the town ... and it's expected they'll keep the party going throughout the weekend.

Harper and Goff first went public with their relationship way back in 2019 -- when TMZ Sports spotted them running errands at a Los Angeles-area Best Buy. They've since become inseparable -- even when the quarterback got traded from the Rams to the Detroit Lions.