| Neptune's Shell
| Max stack
|| Transforms the holder into merfolk when entering water
is a Hardmode Accessory
that aids underwater
performance by allowing indefinite breathing underwater, enabling swimming via the jump key, and eliminating the usual slow movement speed caused by water.
Entering water with this accessory equipped transforms the player into Merfolk, a buff with no time limit. While in this form, Water's usual effects are all eliminated. The breath meter is eliminated entirely, and movement through water is as quick as it would normally be on dry land. Holding the jump key also makes the character swim (fly continuously upward) in water, while falling is just as fast as falls through the air.
Neptune's Shell can be considered an upgrade from the Diving Gear in most respects.
 Used in
- Wearing the Fish Bowl will not activate the Merfolk buff.
- Swimming speed nears that of flying through air with Wings.
- Swimming in Honey activates all the perks of Merfolk but does not allow you to move at full speed.
- However, swimming in Lava does not.
- Landing in and "jumping" from water alone (by swimming up past the surface), without touching land, does not reset flight time for Wings, Rocket Boots, or Spectre Boots.
- The Merfolk form overrides all clothing and equipment graphics. No armor or clothing will show on your character while Merfolk is active.
- The Merfolk buff overrides the Werewolf buff, replacing the graphics and cancelling the bonuses granted by the Moon Charm during the night.
- The Merfolk form is affected by Dyes.
The player will still be visible if they drink an invisibility potion and enter the water with a Neptune's Shell active.
If in water, with auto-pause on, opening the inventory will display your normal form rather than the Merfolk form.