The second boss level in HTFA 5. In the completely submerged part of the ruins in Aqua Kingdom, you have to face against a huge snake before you can proceed to the next kingdom.
The boss room is completely filled with water, so you have no choice but to swim during the fight. The level's layout itself consists of four Heart items for health recovery and an extra life on the left side, on the lower corner. The right side consists of two passages where the snake can show up. Giant Snake will always begin on the lower passage when you begin the level, then it moves backwards after some time only to later show up on the other passage. Aside from causing collision damage to the playable characters, the snake can attack by shooting a stream of fireballs to the player.
To defeat it, you have to shoot its head enough times.