Christie Brinkley and John Mellencamp took their relationship to the next level -- hanging together at his fabulous island estate ... yet in true Mellencamp fashion it still had a down home feel.
The couple was all hugged up on a dock on Daufuskie Island ... offshore from Hilton Head, SC. Christie hopped a water taxi on Wednesday back to the mainland after what had to be a fabulous getaway to John's island retreat.
The rocker remodeled an old country estate home on the island back when he was with Meg Ryan. The place is so fancy now, it's been written up in Architectural Digest.