Ryan Reynolds & Sandra Bullock Vacationing Together ... NATURALLY

8/17/2011 9:45 AM PDT

Ryan Reynolds & Sandra Bullock On Vacation, Take a Hike in Wyoming

Sandra Bullock and Ryan Reynolds hooked up ... for a friendly hike in the Wyoming wilderness -- along with Sandy's adorable son Louis Bardo.

Ryan carried Louis in a backpack during the nature walk through Grand Teton National Park last weekend.

The trio is vacationing in Jackson Hole with a few other friends, but we gotta ask ...