The Jetpack is a rare accessory that is immensely helpful in traversing the dungeon.
It can be found inside certain shops, as a very rare drop from a crates or by bombing the wall behind the Alien Lord in the UFO Crash Site level of the Ice Caves. As with all items, it may also be found buried in random walls, visible only with the Spectacles.
It cannot be equipped at the same time as a cape; picking one up will automatically drop the other if you have it.
A jetpack bought in a shop costs $18,000 plus a level inflation of $2,000, making it the game's most expensive item besides the Ankh.
It allows you to fly in any direction by pressing the jump button in mid-air.
The duration of each 'boost' is limited to a few seconds of thrust. If this runs out during flight, the Spelunker will fall out of the air.
The boost recharges immediately when your feet touch the ground, but not when you grab onto a ledge or a wall with the climbing gloves.
The jetpack does not run out of 'fuel', so can be used infinitely as long as the boost is allowed to recharge.
Note that the maximum height reachable with a single jetpack boost is high enough to cause falling damage if you land on or below the level you took off from, so be careful when flying upwards if there is no ledge in sight to land on.