Explosive

An Explosive is a type of weapon that detonates after a set amount of time, an impact, a trigger, or a remote detonation. It releases a substance to implicit damage or as a distraction.

Overview
Explosives are most commonly used as projectile weapons in order to ensure the user's safety. The Marines and several pirate crews use cannonballs that contain an explosive material that detonate upon impact or when damaged.

Some explosives contain a substance that provides a way for escape like smoke bombs.

Bombs
Bombs are the most common explosives. Several bombs were seen in the series, varying in size and containing the substance. Most bombs are named after their contained substance.

Smoke Bombs
Smoke Bomb, as the name suggests, is a type of bomb that upon impact create a smokescreen, allowing its user to escape or attack their opponent unnoticed. Higuma used a smoke bomb to escape the Red Hair Pirates with Monkey D. Luffy as a hostage.

Poison Bombs
Poison Bombs are a type of bomb that upon detonation release a poisonous substance. One such bomb was used by Krieg in his battle against Monkey D. Luffy.

Flash Bombs
Flash Bomb is a type of bomb that upon detonation release a strong flash of light to blind the user's target and allowing its user to escape or attack their opponent unnoticed.

Flash bombs were disguised as "Flash Barrels" by Gekko Moriah and were used to fool nearby travelers to give away their location inside the Florian Triangle.

Bomb Collar
The Bomb Collar is a device strapped around the neck of slaves. They are connected to a chain, which if broken, will cause the collar to explode.

Canonballs
Cannonballs are the most common explosives shown in the series. The Marines and several pirate crews use cannonballs that contain an explosive material that detonate upon impact or when damaged.

Buggy and Muggy Balls
Buggy balls are a special type of bomb, created and used exclusively by Buggy and his crew.

The Muggy Ball is a smaller version of the Buggy Ball.

Dynamite
Dynamite is a type of explosive that is detonated by heat. It is usually shaped like a cylinder with a fuse at its end, called a "Stick of Dynamite". The cylinder contains the explosive material, and the fuse is then ignited. When a cinder reaches the explosive material, it creates an explosion. Dalton was shown with several sticks of dynamite strapped to his body.

Grenades
A grenade is a kind of explosive that detonates after a short amount of time after a pin trigger is pulled from it. Similar to bombs, grenades can contain several materials that the grenade is named after, like flash or poison.

Bomu Bomu no Mi
The user of the Bomu Bomu no Mi can turn any part of his or her body into a bomb.

Nikyu Nikyu no Mi
The Nikyu Nikyu no Mi can make a bomb made of air pressure called the Ursus Shock.

Pika Pika no Mi
While the Pika Pika no Mi's main power is light, its user can send a beam that can cause an explosion upon impact. That was demonstrated by both the actual fruit user, Borsalino, and 'users' of an artificial alternative, the Pacifista.

Pamu Pamu no Mi
The Pamu Pamu no Mi is a Paramecia-type Devil Fruit that allows the user to cause their own body or any inorganic object they touch to rupture and explode. It was eaten by Gladius.

Usopp's Arsenal
Usopp used several explosive pallets in his arsenal, containing substances ranging from spices, spikes, and small explosives.

Dials
Several dials were shown to have a similar affect as some explosives or infused with weapons to give said weapon explosive properties.

Shinokuni
Shinokuni was a chemical weapon created by Caesar Clown from the previous chemical weapon detonated on Punk Hazard.

Dyna Stone
The Dyna Stones are weapons which are said to be equal to the Ancient Weapons. Z used the Dyna Stones in his Grand Reboot plan. Naomi Drunk used small Dyna Stones as arrow heads to create arrows that explode on impact.

Trivia

 * The Tamatebako, a national treasure of the Ryugu Kingdom, was planted a bomb that detonated upon opening.