Next you have to get high enough in the air so that you unload all the underground caves, so 128 blocks at minimum. That’ll concentrate all the spawns to inside the farm. Spawner traps are a type of mob farm that uses a spawner.They employ the mob spawners found in dungeons as a source of mobs.The purpose of these traps is to create an infinite source of items which can be gathered in an efficient way from the mobs spawned by the monster spawner. Drowned spawn in river biomes at a significantly higher rate than in the ocean, so if you can find one wide enough build it there first.