Geysers are traps that shoot a wall of fire when triggered with wire. This trap does not consume any ammunition, its output being limited to only how frequently it can shoot a wall of fire, which is every ~3.33(3 1/3) seconds. Geysers have a range of approximately 20 blocks, similar to Flame Traps. Geysers are placed during world generation in random areas on the Cavern layer, presumably deep enough where lava may spawn. Unlike the Flame Trap, Geysers do not cause the On Fire! debuff.
If a Geyser is blocked by less than 29 other solid blocks with no opening of at least 4 vertical blocks and 2 horizontal blocks, including liquids, it will simply pass through them signaled by puffs of smoke moving through the blocks (the puffs will still damage when touched), starting the wall of fire at the first opening. Geysers can face upward or downward (depending on placement), but not sideways. Geysers do not break anything liquid normally breaks.