- "Is that so... Well, let me know if and when you have need of a bomb that explodes underwater."
- — Zora
Water Bombs are items from The Legend of Zelda: Twilight Princess. This specialty bomb retains all of the functionality of the regular bomb with the added ability of underwater usage. Bomb Fish appear to be the inspiration for the bombs, as they explode if Link hits them with his sword and are identical in appearance. Water Bombs are needed in order to enter the Lakebed Temple.
Water Bombs can be purchased from Barnes in Kakariko Village after Link receives a letter from Barnes regarding a new type of bomb. They can also be purchased from a Zora next to the temple at the bottom of Lake Hylia. Only fifteen can fit in one of Link's Bomb Bags. Water Bombs can also be combined with the Hero's Bow to create Bomb Arrows that explode upon contact.
Interestingly, if Link catches a Bomb Fish with his Fishing Rod, he can use them as Water Bombs.
Domesticated Bomb Fish
Given the fact they have the same general appearance and the fact Link can use them as Water Bombs after catching one with his Fishing Rod, it is likely that Water Bombs are simply Bomb Fish that have been domesticated (most likely by the Zora due to the fact normal bombs don't work underwater) to be used as Water Bombs. One reason why they are claimed to be a new type of Bomb, may have been to conceal the fact from the general public that Bomb Fish can be caught and stored in a Bomb Bags to be used as Water Bombs (and thus can be obtained for free). This may also explain why they are forbidden from being recorded in the Fish Journal as it was likely done to protect the Bomb Fish from being driven to extinction by over fishing and protect wild populations of Bomb Fish (in order to maintain a healthy breeding population to make more Water Bombs). If true, this would make Bomb Fish similar to Bomblings (another type of living bomb).
Water Bombs appear as one of the Item Cards used to uncover secrets in Adventure Mode. They are primarily used on rocks within areas covered by water in order to reveal a secret. Like all Item Cards, characters, and enemies on the Adventure Map it is represented by an 8-bit sprite.