Dennis Quaid's 26-Year-Old Girlfriend Appears to Flash Engagement Ring

Dennis Quaid seems ready to walk to the altar again -- the guy's reportedly engaged to his WAAYYY younger girlfriend ... and we got what looks like the first photo of the ring.

TMZ has obtained a photo of Dennis with his 26-year-old GF (and now, apparent fiancee), Laura Savoie, holding up her left ring finger, which has a giant rock on it. We're told this photo was taken Friday night minutes after DQ proposed to her at Turtle Bay in Oahu.

Apparently, a wedding party was happening nearby, and a couple that had just gotten hitched invited Dennis and Laura to pose for a pic to celebrate the dual occasions. Mazel!!!

Laura's a grad student at the University of Texas. She and Dennis have been going out since the summer, so Dennis -- who's 65, BTW -- must truly be head over heels for this gal.

As we reported ... Dennis and Laura were spotted vacationing in Hawaii just earlier this week, where they were getting their paddleboard on at Waikiki Beach. They've been seen out together a lot, notably in August while boating on Lake Como in Italy.

This would be Dennis' fourth marriage -- he's been hitched to Kimberly Quaid, Meg Ryan and P.J. Soles, and had children with the former two women.