For the game mechanics in Bloons TD 6, Bloons TD Battles 2, and Bloons Adventure Time TD that are commonly referred to in-game as obstacles, see Line of sight and Removable.

Obstacles are a puzzle element in Bloons Pop!.

In the Bloonspedia, Obstacles are categorized as Bloons.

List of Obstacles

edit
Image Text Bio Best choice Not recommended
  Brick Obstacle
Stops your shots
Hit these bricks multiple times to destroy them. Phoenix, Captain Churchill, Gwendolin, Obyn Greenfoot, Acid Gunner, Mortar Monkey
  Rubber Obstacle
Shots will bounce off this
Shots bounce off these rubber blocks with additional speed. Lightning Storm, Captain Churchill, Obyn Greenfoot, Quincy, Striker Jones, Super Monkey
  Decaying Rubber Obstacle
Bouncy block that can be broken
Shots will bounce right off these blocks, but multiple hits will destroy them. Phoenix, Spiked Ball Storm, Gwendolin, Dart Monkey, Wizard Monkey
  Metal Obstacle
Tough blocker that your shots cannot break
Shoot around these blocks as they will reduce the power of your shots. Phoenix, Captain Churchill, Gwendolin, Obyn Greenfoot, Acid Gunner, Mortar Monkey
edit