Oil Drums (usually referred to as Explosive Barrels) are common landscape objects first appearing in Worms 2, and later in almost every other Worms game. If an Oil Drum is hit by a Worm's weapon, a Land Mine, or make contact with a sufficient amount of fire (2nd generation games only), it'll explode and scatter fire to the surrounding area, which extinguishes after a few seconds. If it makes contact with only a small amount of fire, it'll heat up and become more unstable instead of immediately bursting, which is indicated by the sprite's color getting whiter as it heats up. There are three stages of this heating (with the Oil Drum becoming whiter and whiter each stage), after the third one, the Oil Drum explodes.
Oil Drums can apply extra power and force to an attack, so if there is an Oil Drum near an enemy Worm, it is recommended to attack that Worm so the explosion of the Oil Drum along with the fire adding even more damage would normally kill the Worm instantly. Because of this, players usually try to get their opponents close to Oil Drums, and then attacking them. This can be done in several ways, mostly using the Ninja Rope and knocking the surrounding Worms to the desired position, or by using the Shotgun's or the Longbow's first shot to hit the foes as close as possible, then the second to blow up the Oil Drum. Its fire can also be used to drown the enemy, or to knock them onto a nearby Mine.
When the Oil Drum is sitting on a bridge, if the Worm shoots right under it with a Shotgun, the Oil Drum won't explode, but it will fall down, where it can be blown up with the second shot. However, the Oil Drum can normally only move vertically downwards - despite that when landing, it bounces up a few times. It can't be moved by a Worm, so one would have to look out to not become stuck under it. Despite this, a Worm can, under certain circumstances, overlap with an Oil Drum, and two or more Oil Drums can also overlap with each other.
The Earthquake is the only thing that can move the Oil Drum in horizontal directions.
Depending on their positions, Oil Drums can detonate each other, resulting in a chain reaction of explosions and flames, usually killing several of the Worms nearby, and greatly changing the surrounding terrain.
- Worms 4: Mayhem and Worms: Ultimate Mayhem do not feature fire, therefore Oil Drums are poisonous instead. The fire is replaced with green venomous smoke. The large flame icon on the Oil Drum is also replaced by a black skull inside a yellow warning sign.
- In these two games, Oil Drums can also be dragged and moved around with the grappling function of the Ninja Rope, which makes both Oil Drums and the Ninja Rope extremely useful since several types of strategies can be implemented with them together.
- Although present in Worms 2, Oil Drums were not a Scheme option. They appeared in some missions but in order to have them present for regular play, players needed to type "OnDeadlyGround" (case sensitive) into the landscape editor to get them to appear. In the patch, this was made a Scheme option.
- In Worms Revolution onward, the Oil Drum's green color was changed to blue. The large flame icon remained the same.