In the third season opener, Nick Jonas joins Bear for a snowy mountain adventure in the Sierra Nevada during blizzard conditions. The guys rappel down a sheer cliff, eat a frozen bird and swim across a freezing lake.

Julianne Hough joins Bear on a trek in Africa, where they encounter a pack of elephants blocking their path. Other challenges include dealing with big cats and a snake; rappelling from a cliff; and navigating waterfalls.

Courteney Cox joins Bear in Ireland, where they climb jagged peaks, descend sheer cliffs, battle the cold and feast on maggots.

Shaquille O'Neal joins Bear in the Adirondack Mountains of Update New York, where they deal with dense forest, leeches and steep cliffs.

Lindsey Vonn joins Bear on the French island of Corsica, where they rappel down a rock wall, use a spear gun, swim and dine on sea urchins.

Mel B (aka "Mel B") joins Bear in Wales, where they navigate cliffs, cross challenging terrain and tackle a huge descent. Included: Mel administers unconventional first aid to Bear, after he gets stung by a jellyfish.

Marshawn Lynch joins Bear on the French island of Corsica, where they chase a wild hog, navigate cliffs and encounter the French Foreign Legion.

Actor Sterling K. Brown (of This Is Us (2016) fame) joins Bear in the high mountains of Colorado, where they battle plummeting temperatures while descending a sheer rock face, track an elusive deer and rappel down a waterfall.

Julia Roberts joins Bear Grylls in Kenya, where they navigate a harsh landscape of desert, canyons and rivers to deliver vaccines to a remote village.

After a breathtaking repel from a helicopter, Bear and Hollywood sweetheart Vanessa Hudgens evade a boulder avalanche, summit a massive dormant volcano, and come face-to-face with a rattlesnake, which makes for a cringe-worthy dinner. Along the way, Vanessa shares insights on her meteoric rise to stardom and draws strength and determination from the memory of her late father.