These characters are explorers and adventurers, so versatility with their attire is key because they won't know what their exciting day brings them while on the job.  So tactical field wear is optimal. Also, some adventurers have villains after them while on missions and expeditions, so a few weapons and/or whips won't hurt. 
Adventurers should opt for an Indiana Jones inspired look with the fedora, whip, and attitude. 

Tomb Raiders should go for the huntress or hunstman inspired costumes, the black widow or other catsuit and you'll also need some weapons to fight your villains.

Anthropology professors can opt for the paleontologist or safari/zookeeper costumes with a safari or fedora. Think about Indiana Jones on break at the university teaching classes and spending time in his (or her) lab analyzing his finds.

Hunters can wear any of the above or wear the Jane the Hunter or other hunter costumes.