1

Armed guards

2

Assassins

3

Bandits or pirates

4

Concealment, deception, or secrecy

5

Curse (real or imaginary)

6

Deadly environment

7

Dishonesty and greed of populace

8

Great distance

9

Inscription that needs translated

10

Lack of supplies

11

Limited time

12

Looming natural or unnatural disaster

13

Magical wards or guards

14

Monster

15

Native cannibals or headhunters

16

Physical barrier

17

Riddle that must be solved

18

Roaming savage beasts

19

Thieves

20

Wrong or misleading information