Here is the full list of all 26 Delver achievements.
Make it through the Ruins
Zap wands 300 times in one run.
Make it through the Sewers
Find 300 gold in one run.
Kill 150 monsters in one run.
Max out on belt slots.
Identify 5 items in a run.
Trip 10 traps in one run.
Listened to the wise.
Use 15 potions in one run.
Make it through the Caves
Bought something from the wizard.
Bought something from Joff.
Buy a belt slot.
Buy a backpack slot.
Make it through the Dungeons
Died, for the first time.
Escaped with the Orb.
Grab the orb.
Max out on backpack slots.
Chow down on 40 things in one run.
Use 10 scrolls in one run.
Take 400 damage in one run.
Become poisoned 10 times in a run.
Find 5 secret areas in one run.
Buy a magical elixer from Joff.