The Giant Tortoise is a HardmodeJungleenemy. It walks around slowly, and occasionally retracts into its shell. It then starts spinning and hurls itself at the player, gaining increased defense and dealing high contact damage. It drops Turtle Shells, which are vital for crafting Turtle armor (an ingredient of the near-endgame Beetle armor).
A functionally identical variant of the Giant Tortoise, the Ice Tortoise, can be encountered in the Ice biome.
The cooldown between spin attacks is 6.67 seconds by default. It is reset if the Giant Tortoise takes damage.
If the Giant Tortoise is more than 12.5 tiles away from the player and has an unobstructed line of sight to them, the cooldown is reduced to 1.33 seconds.
If it is more than 37.5 tiles away, and has an unobstructed line of sight or is no more than 12.5 tiles above them, it is further reduced to 0.61 seconds.
If in water, the Giant Tortoise will use its spin attack continuously.
Each spin attack consists of half a second of retracting into the shell, spinning for 1.5 seconds, then decelerating until coming to a stop on a solid surface, and coming out of the shell for half a second again. Attacking a Giant Tortoise at any time cancels the spin attack.
Although the trajectory of the Giant Tortoise during its spin attack is determined the moment it retracts into its shell and is based on the player's position at that time, the enemy does recognize the player's current position, and will slow down very quickly and attempt to drop down as soon as it is above the player.
Any weapon with a high rate of attack is effective, as it prevents the Giant Tortoise from using its spin attack. Viable options include the Megashark or a yoyo.
Melee weapons are useful as long as the player stays close to the Giant Tortoise. Even when not attacking continuously, the spin attack cooldown is much higher at close range.
Pools of water should be avoided, as they cause the Giant Tortoise to immediately charge at the player.
Giant Tortoises cannot drop through platforms. Setting up several rows of long platforms significantly reduces the danger of the spin attacks.
Giant Tortoises can be farmed much easier on the surface than in the Underground Jungle because of the larger area of space to spawn on. Alternatively, a large area can be dug out underground and summon weapons, e.g. the Pirate Staff, can be used to farm in either location.
This enemy, as well as its Ice Tortoise variation, appears to reference Tatori, a similar tortoise enemy in the action-adventure game Super Metroid that also attacks the player with the same flying spin.
Despite being called the Giant Tortoise, it drops Turtle Shells.