I'll use some notable figures from the time like Charles Darwin the famous zoologist who birthed the idea of natural selection as an explanation for evolution, and Joseph Nicollet, the French explorer who mapped the Mississippi.
http://tvtropes.org/pmwiki/pmwiki.php/Main/CharlesDarwin
Zebulon Pike - American - early 19th Louisiana Purchase (United States)
Meriwether Lewis - American - 18th/19th - western United States
William Clark American - early 19th - western United States
Joseph Nicollet - French/American - 19th - Mississippi and Missouri Rivers
Jim Bridger American 19th Western United States
Alexander Forbes British 19th California
John C. Frémont American 19th Oregon Trail, Sierra Nevada
John Franklin - British - 19th - Northwest Passage
David Thompson British 18th/19th Western Canada, Pacific Northwest
Thomas Coulter Irish 19th Mexico, Alta California
William Lewis Herndon - American -19th - Amazonia
Henry Walter Bates British 19th Amazonia
Juan Galindo mixed 19th Mesoamerica (Mayan remains)
Alexander von Humboldt German 19th Latin America, Siberia
Archibald Menzies - British - 18th/19th - Pacific Ocean, circumnavigation
Matthew Flinders British 18th/19th Australia, Tasmania
Robert O'Hara Burke Irish 19th Australia
David Livingstone British 19th southern and eastern Africa
Pierre Savorgan de Brazza Italian/French 19th Congo
Hermenegildo de Brito Capelo Portuguese 19th African continent
Adrien de Gerlache Belgian 19th/20th Antarctica, Arctic
Francis Garnier French 19th Mekong River
It's not uncommon for the explorers of the time to be military personnel. The fact they're exploring unknown teritories almost demands that they know how to handle themselves and others in combat, better to be safe than sorry.
http://www.enchantedlearning.com/explorers/1700.shtml
http://www.enchantedlearning.com/explorers/1800.shtml
As of late though David Attenborough is widely known for his voice-over work and documentaries, appearing in some of the best nature-documenteries ever made. He is thought to have inspired the character Nigel Thornberry in the cartoon series The Wild Thornberrys
His overall apperance is inoffensive white hair and laid back attire like a loose collared shirt, usually light coloured clothing.
Nigel Thornberry wears traditional colonial clothing worn in the Middle East or Africa, most notably his pith helmet.
http://www.qub.ac.uk/imperial/key-concepts/Exoticism.htm
http://tvtropes.org/pmwiki/pmwiki.php/Main/BoisterousBruiser
http://tvtropes.org/pmwiki/pmwiki.php/Main/BoldExplorer
http://tvtropes.org/pmwiki/pmwiki.php/Main/AdventurerOutfit
http://tvtropes.org/pmwiki/pmwiki.php/Main/TheReliableOne
http://www.whalingmuseum.org/learn/research-topics/overview-of-north-american-whaling/american-whaling
http://www.cavetocanvas.com/page/3 fur trappers
http://osborneradloff.blogspot.co.uk colonial
