- George Kourounis
- Â Self - Host 48 episodes, 2007-2016
- Mark Robinson
- Â Self / ... 4 episodes, 2007-2008
- Doni Wijayanto
- Â Himsef - Volcanologist / ... 2 episodes
- Gary England
- Â Self - Meteorologist 1 episode, 2007
- Jacques Durieux
- Â Self - Volcanologist 1 episode, 2007
- Mark Donovan
- Â Self - Firefighter 1 episode, 2007
- Hinsperger Chris
- Â Self - Cave Guide 1 episode, 2007
- Doc Ines
- Â Self - Divemaster 1 episode, 2007
- R.J. Evans
- Â Self 1 episode, 2007
- Gernot Dick
- Â Adventurer / ... 1 episode, 2007
- Bob Gladden
- Â Self - Shark Photographer 1 episode, 2007
- Pastor Isaac
- Â Self - Pastor 1 episode, 2007
- Samuel Gasana
- Â Interpreter / ... 1 episode, 2007
- Scott McPartland
- Â Self - Storm Chaser 1 episode, 2007
- Ian Rees
- Â Self - Storm Chaser 1 episode, 2007
- Chris Thompson
- Â Self - Ship Captain MV Horizon 1 episode, 2007
- Mike Theiss
- Â Self - Storm Chaser 1 episode, 2008
- Ben Cropp
- Â Self - Underwater Explorer 1 episode, 2008
- Alasdair Russell
- Â Self - Caving Team / ... 1 episode, 2008
- Ariel Kleber
- Â Mechanic / ... 1 episode, 2008
- Lance Mackey
- Â Self - Dog Musher 1 episode, 2008
- Bill 'Cave Man Bill' Donaldson
- Â Self 1 episode, 2008
- Eduardo Fernandez-Aguera
- Â Self - Ultra Runner 1 episode, 2008
- Jim Leonard
- Â Self 1 episode, 2008
- Gerard Fryer
- Â Self - Geophysicist, Pacific Tsunami Warning Center 1 episode, 2008
- Stephen Reynolds
- Â Self - Yukon Quest Race Director 1 episode, 2008
- Dick Whitaker
- Â Self - Meteorologist 1 episode, 2008
- Tony Morley
- Â Self - Caving Expedition Leader 1 episode, 2008
- Steve Reifenstuhl
- Â Self - Ultra Runner 1 episode, 2008
- Diane Van Deren
- Â Self - Ultra Runner 1 episode, 2008
- Charles Ouellet-Pelletier
- Â Archeologist / ... 1 episode, 2008
- Jimmy Deguara
- Â Self 1 episode, 2008
- Charlie Callagan
- Â Self - Park Ranger 1 episode, 2008
- Anthony 'Woofie' Humpage
- Â Self - Ultramarathon Medical Team 1 episode, 2008
- Chris Kostman
- Â Self - Race Director 1 episode, 2008
- Richard Anderson
- Â Self - Ultra Runner 1 episode, 2008
- Richard Graham
- Â Self - Bridge Climb Guide 1 episode, 2008
- Heinz Kallin
- Â Self - Off-Road Driving Expert 1 episode, 2010
- Rob Jutson
- Â Self - The Explorers' Club 1 episode, 2010
- Phil Nuytten
- Â Self - Marine Archeologist 1 episode, 2010
- Chris Harvey-Clark
- Â Self - Marine Biologist 1 episode, 2010
- Manuel Galvez
- Â Self - Cave Team 1 episode, 2010
- Nik Halik
- Â Self - Adventurer 1 episode, 2010
- Jochen Neugebauer
- Â Self - Off-Road Driving Expert 1 episode, 2010
- Kristen Sarah
- Â Guest Star 1 episode, 2015
- Kartikeya Singh
- Â Guide / ... 1 episode
- Dan Wyman
- Â Self - USAF Hurricane Hunters 1 episode
- Gylfi Saevarsson
- Â Self - Mountaineers of Iceland 1 episode
- Steve Axford
- Â Self - Volcano Photographer 1 episode
- Enrico Pellegrini
- Â Self - Site Manager MOSE Project 1 episode
- Jorg Wilz
- Â Self - Mountain Guide 1 episode
- Ross Velton
- Â Self - Travel Writer 1 episode
- Mario 'Zaza' Zaia
- Â Self - Stromboli Guide 1 episode
- Ólafur Ragnar Grímsson
- Â Self - President of Iceland 1 episode
- Martin Fichtl
- Â Self - Mountain Guide 1 episode
- Fantasy Dan
- Â Self - Pilot 1 episode
- Jordan Smith
- Â Self - Instructor Surf Sister 1 episode
- Danielle Ellis
- Â Self - USAF Hurricane Hunters 1 episode
- Brian Jones
- Â Self - Mountain Guide 1 episode
- Bob Freer
- Â Self - Everglades Alligator Farm 1 episode
- Dave Schubert
- Â Self - Mountain Guide 1 episode
- Shannon Halls
- Â Self - USAF Hurricane Hunters 1 episode
- David Jones
- Â Self - Meteorologist Environment Canada 1 episode
