How found:

   A) After 10 P.M. on the Final Day, go to West Clock Town and enter the antiques shop. Buy the stolen bomb bag for 100 Rupees. (You'll need the Adult Wallet in order to carry enough Rupees.)

   B) As human Link, go to North Clock Town on midnight of the first day. Wait until the old lady from the Bomb Shop enters. A thief will knock her down and run off with her bag of goods, so give chase and hit him with your sword to make him drop the bag. The following morning, go to the Bomb Shop in West Clock Town. Buy the big bomb bag for 90 Rupees.

    How used: Increases bomb capacity to 30.