From 300 feet underground with Tom Hanks to Bora Bora with Jon Favreau and Vince Vaughn, the White Sands desert with the 'Transformers' crew and visiting the far reaches of Sierra Leone, ET's own Mark Steines recalls some of his favorite interviews and experiences of 2009, and you'll never guess which adventure touched him the most!

Talking with Tom Hanks on the set of 'Angels & Demons' 300 feet below the surface at CERN in Geneva, Mark says, "He is so charismatic. He is so good with the press, but we found him in rare form there. He was talking about particle physics, he was talking about antimatter, he was talking about the Illuminati as if he created all this stuff. He's so well versed in it."

Of the explosive, high-octane 'Transformers: Revenge of the Fallen' set at White Sands, NM, with Shia LaBeouf, Megan Fox, Josh Duhamel and director Michael Bay, Mark says, "Everything starts blowing up, the actors start going everywhere, gunshots are going off, and I was like, 'I was wired for this!'"

Mark also talks about his goodwill trip to Africa with Patricia Heaton and dozens of medical volunteers: "I set out on my own journey to Sierra Leone in April of this year. It was a way for me to put something good back into the world. … I wanted to document a medical team's insertion into this country and see what they do. I wanted to remove myself from in front of the camera and get behind the camera -- something I'm very passionate about. What I saw there left me speechless. There are so many things in this impoverished country that need attention." Mark's book on the experience is called See the Light: A Passage to Sierra Leone.

Mark also ranks his one-on-one with Sandra Bullock on the Atlanta 'The Blind Side set as one of his most memorable of the year. Watch the video!