These two tricks stem from the same base - getting OOB in the Zora's River area - and thus they are combined together here despite being incredibly different in usage. Iza 1 Skip skips the boat ride down Zora's River after agreeing to help Iza and blowing up the rocks at the beginning. Done with the fast strats this saves 20 seconds in categories that need to earn Iza's bomb bag. Infinite Bomb Arrows allows you to make the capacity of your quiver and bombs infinite, which by itself can be useful for completing the Cave of Ordeals, but has further uses as well involving BiT.
Once you have the setup you need, warp to Lake Hylia and howl at the hawk grass to start Plumm's minigame. Inside the minigame, clip OOB with the kargarok using either of the clips linked below (the first clip is fastest, the second one slightly slower), and crash the Kargarok while OOB. Link should void out OOB (if Link does not, see the description below for the backup strat), and respawn on an OOB ledge past the end of Zora's River.
Original video by isaac_twpr here
Ideally, the kargarok will bonk and drop Link out of bounds. On a late dash, the kargarok will go through the wall, which can be backed up by bonking on the scaffolding shortly afterward.
If you can't reach the first OoB crash spot, there is a fast backup here.
For Iza 1 Skip, you will now want to transform into Human Link wearing Zora Armor and roll jump into the water. Swim forward and you will hit the loading zone at the end of the river to finish Iza 1.
For Infinite Bomb Arrows, dash off the ledge and jump into the water as Wolf Link. You will appear in the canoe as Wolf Link and ride down the waterfall into Lake Hylia. From here, Iza's Zora Assistant will ask you if you want to try again. Say "Yes" and you will arrive back in Iza's Hut as if the minigame were restarted, but you will not be in the canoe. You can now warp anywhere and your bomb and arrow counts will be infinite.
An alternative method to the Kargarok OOB clip and subsequent OOB crash is to crash the kargarok inbounds and fail Plumm Minigame. When you respawn on the dock in Lake Hylia, Plumm will ask if you want to play again. Say "No", transform into Human Link, and swim to the GCN right wall (Wii left). Once you get near the sloped bank, pull out the Clawshot, hold Target, and swim towards the wall to clip through it. Swim out in the OOB water until you reach the edge, and void out.
When you respawn, you will notice that Plumm reappears and asks if you want to play his minigame again. Say "Yes", then crash the kargarok again. If you do not void out immediately after crashing the kargarok, walk forward and fall off the OOB ledge to void out. From here, you will respawn on the OOB ledge, and can follow the appropriate steps above.
A video of this strategy: