Sanda Bullock, Ryan Reynolds & Louis: Hiking Buddies!

Enjoying each other's company in the great outdoors, Sandra Bullock and her adorable son Louis were spotted hiking through Wyoming's Grand Teton National Park with Ryan Reynolds over the weekend.

According TMZ's pictured report, the "Proposal" co-stars took to the rugged terrain together while the 34-year-old "Change-Up" hunk toted little Louis in a backpack carrier.

While the two are said to be vacationing with pals at nearby Jackson Hole (where Sandra's family has a home), sources say the pair are nothing more than friends, as they explained, "They've been buddies for over 10 years now."

Another insider added, "They are like family, like a brother and sister. It's not a love affair. They've been friends for over 10 years, and they care for each other deeply. They support each other and have a lot of fun together."