Treasure hunters are given an encrypted clue that leads them to their next clue.
A simple encryption is to replace each letter with the next letter of the alphabet (a becomes b, b becomes c and so on to z becomes a). This is a good encryption provided the hunters recognise what has been done. Alternatively a key could be given that maps out which letters have been swapped. The hunters could be given something like this (maybe with a previous clue?) to use to decrypt the clue:
| A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | V | U | V | W | X | Y | Z |
| X | C | V | I | S | P | B | D | H | A | W | L | R | O | Q | F | K | T | N | Y | J | Z | E | U | M | G |