The pen I’d like to recommend for that purpose is the legendary Fisher Space Pen. First, let’s satisfy our inner geek with the story of how the Space Pen was designed by the Fisher Pen Company for use during space travel. Yes, SPACE TRAVEL! I don’t know about how demanding your travel style is but if this baby can withstand the cold of space, the heat of re-entering Earth’s atmosphere, the variable atmospheric pressures of 0g up to a possible 12g of ballistic reentry, well… I’d say the Space pen has my travel needs covered.