Isma's Tear

Isma's Tear is an Ability in Hollow Knight. It allows the Knight to swim in acid without taking damage.

Function
Although very useful, Isma's Tear is not necessary to complete the game. Obtaining it allows access to the following: It is also useful while exploring Fog Canyon and fighting Uumuu.
 * Shape of Unn in Greenpath
 * Access to Fog Canyon through Forgotten Crossroads or Fungal Wastes
 * A Grub in Isma's Grove
 * Access to the Queen's Gardens
 * A Grub as well as a shortcut in Kingdom's Edge

How to Acquire
Located in Isma's Grove in the Royal Waterways. Accessing this area requires Crystal Heart and beating Dung Defender.

Trivia

 * Dung Defender refers to it as "Isma's Blessing".