Boom Beach Wiki
Boom Beach Wiki
"The mine wasn't dangerous enough, so they put a cannon on it! Potent defensive cannon that when destroyed detonates with a powerful explosion, causing damage in an area."

Mark 1 Mark 2 Mark 3


  • The Flotsam Cannon is a Prototype Defense that can be built inside the Weapon Lab.
  • Like other prototype defenses, it will only last for a limited duration after being deployed.
  • The Flotsam Cannon is a defensive cannon that deals high damage per second with a small splash radius. When it is destroyed, after a short delay, it will explode, causing massive damage to everything in an area. This includes both troops and buildings. It will also trigger Mines, Boom Mines, and Shock Mines.
    • The area of effect is visible after the building is destroyed. It is represented with a circle with a skull image inside it.
    • This damage value is not boosted by Ice Statues.
  • The Flotsam Cannon has a small blind spot where it cannot fire upon, similar to that of a Machine Gun.

Offensive Strategy

  • The Flotsam Cannon is essentially a weaker Doom Cannon alone with a higher rate of fire. That being said, it is deadly enough for you to consider scattering your units.
  • Never ever use melee units such as Warriors against this defense despite the Flotsam Cannon’s blind spot, because when they destroy it, any buildings left nearby will stall them, likely destroying anything that isn't a Scorcher. To counter this, time a Flare correctly so it takes place right after the Flotsam Cannon is destroyed.
  • A Flare can move troops to safety if the bomb is about to explode, but you need to anticipate the explosion (for example, by damaging it with Gunboat Weaponry just before it runs out of health) or be very quick. However, this can drastically change your attack if the troops are very spread out, as the Flare will regroup all your troops.
  • Dr. Kavan's Ice Shields ability can protect troops from the deadly blast. Use it just before it explodes to minimize casualties.
  • Since Remote Hack can capture prototype defenses, it can be used to easily take out the Flotsam Cannon, and if it is destroyed, the damage will weaken nearby buildings.

Defensive Strategy

  • Do not place it nearby critical defensive buildings, Mines or the Headquarters, because the explosion will set off mines and damage any buildings caught.
  • While it excels against massed infantry, the Flotsam Cannon has relatively low single target damage, meaning Mechs, Scorchers, and high level Tanks can easily make short work of it. Because of this, it's recommended to place Boom Cannons, Cannons, and other high single target damage defense buildings nearby, although try placing them in such a way to minimize the damage the death explosion will inflict on your buildings.
  • The Flotsam Cannon can be deadly against Heavy-Zooka compositions, as once the building gets destroyed, the Zookas will step into the death bomb, ensuring their demise.

Upgrade Differences

  • At Mark I, the Flotsam Cannon resembles a rather large sea mine, with seaweed both on it and around it, as well as a single starfish. Dynamite fuses are installed all around itself, and there's a circular rail in the middle, assisting the porthole in rotating and firing at enemies. It's painted in a bronze scheme.
  • At Mark II, it now has a metallic casing. The seaweed on it is removed. Rings around the fuses and a circular platform to support it are added, making the fuses below unseen.
  • At Mark III, it gains a proper cylindrical base, and the general color scheme is a blue-green one, as well as all seaweed being removed.


  • This is the only building that, apart from dealing damage normally, can also damage enemies when destroyed.
  • Apart from Hacked defenses, it's the only building that can damage another building.
  • The Flotsam Cannon and the Grappler are the only Prototype Defenses that have a blind area.


Building Size
Attack Speed
Damage Type
Damage Type
Splash Radius
Splash Radius
Bomb Damage Radius
Splash Radius
Bomb Damage Delay
3x3 2.3-10 Tiles 1s Splash 1 Tile 6.5 Tiles 3s
Mark Number
Damage Per Second
Bomb Damage
Build Cost Build Time
Weapon Lab
level Required
Critical Fuse
Complex Gear
Power Rod
Field Capacitor
1 15,000 500 2,000 0 2 0 4 1h 2
2 20,000 650 2,400 2 6 4 0 4h 4
3 25,000 800 3,000 5 2 8 3 12h 5