Here is the full list of all 14 The Journey Down: Chapter Three achievements worth 1,000 gamerscore.
Complete the game
Annoy everyone with the airhorn
Send the monkey to gather all possible fruits
Rescue Professor Moorhead
Escape from the Sisulus airship
Get the Horn of Awaquán
Place the bombs on the skyscraper and escape
Return to St Armando
Raid the Armando Co skyscraper
That's a pretty long drop...
Get free juice from the friendly vendor
Reception must be really bad around these parts