Wall safe

Wall safes are found in the Rogue's Den.

They can be cracked providing you have a Thieving level of 50. Successfully cracking a safe yields 70 thieving experience. A complete list of loot is found below. Beware - if you fail to crack a safe, a floor trap will spring and deal 2-6 damage on you. Bringing a healing familiar such as a Bunyip is recommended, but not needed, since there is a bank just seconds away, where you can get food. A stethoscope is used to increase the success rate of cracking the safe. These can be purchased from Martin Thwait, who can be found wandering around the general Rogue's Den area.

Only after receiving damage (between 2-6 points), players can right-click the floor allowing 2 options: Examine which says "it's the floor"; and Search states that it will temporarily disable the trap, but at the same time drains one Thieving level. This does not however seem to have any effect on whether subsequent thieving attempts will succeed or fail. It is useful to have cheap food, eg. jug of wine to heal with. Re-spawn of the wall safe is mere seconds, making this activity a very fast way to level up. With no failures and fast cracking (one attempt can take from 3 secs up to 10) one could make about 1500 experience points per minute! There are also usually a lot of players training cooking nearby, so one could sell their loot for food, or simply use the everlasting fire to cook raw food the player already has. An alternative option is to buy drinks from the bar above the Den, though the drinks don't heal as much, even though they are cheap.

Cracking wall safes appears to be one of the fastest ways how to get uncut gems.

Loot

 * 10 Coins (common)
 * 20 Coins (common)
 * 40 Coins (common)
 * Uncut sapphire (common)
 * Uncut emerald (uncommon)
 * Uncut ruby (uncommon)
 * Uncut diamond (rare)

Drop rates
Based on my 200 successful attempts sample:

- 10 Coins (42x) - 21%

- 20 Coins (78x) - 39%

- 40 Coins (30x) - 15%

- Uncut sapphire (28x) - 14%

- Uncut emerald (10x) - 5%

- Uncut ruby (10x) - 5%

- Uncut diamond (2x) - 1%

Trivia

 * Wall safe cracking isn't mentioned in Skill Advance Guide