You can make a creeper farm by placing a spawning platform in an ocean to maximize spawning rates. For example, carpet can be placed with 2 blocks between them to block spiders with a minimal loss of spawn area for the creepers. This is easily avoided by removing 3-by-3 areas in the farm.
Be aware some Creeper farms can also spawn Spiders. In Bedrock Edition, this mechanic may not work. This is tall enough to allow creepers to spawn, but short enough to prevent other mobs such as zombies and skeletons. When trapdoors are placed on a 2 block high ceiling, it lowers the height to 1 13⁄ 16 blocks high.
