Sentryman Explorer Pen is what you nee dif you are planning to go on an expedition. The pen is amazingly durable and can withstand all kinds of temperatures and weather. It comes with the ability to glow in the dark and thus you can find it even whe there is no light whatsoever.
Morever, it comes with an artificial flint in the barrel which allows you to create fire when rubbed against magnesium material. How you are going to find magnesium material while on an expedition is something that is worth being discussed. Also, it comes with a luminous cap which allows you to find the pen in the dark.
There also is an anodized barrel which is strong and lightweight and also comes with a palladium plated attribute. All this makes the pen quite a cool deal and it could also double up as a ball pen while functioning as a fountain pen. It was originally designed for explorers of South Pole. Thus, you may want it if you plan to go somewhere cold, dark and dreary to write a journal.