The salvage arm attaches automatically when you get it. refill its life at the ship yard on meracy island. It will cost you but its worth it. Click on menu on the bottom left of your touch screen and click salvage.
to get the salvage arem beat the first two spirit temples then go to eddo's island and scream into to the microphone and he will sell it to you as low as 300 rupees this does not work or maybe it does i do not know(this is a diffrent person i use cheats)
Go to a spot with a cross, there you press 'menu' en then salvage.
Go to eddos island after a certain point in the game. youll know when you can. :) hope that helps.
Canon island where you bought the canon.
You can get the Salvage Arm from the man who sold you the Canon on Canon Island in the Southwestern sea chart region.
You should get a letter Eddo and he will tell you to go to him to get a salvage arm
You use the salvage arm.
you go to molida island.
You can`t obtain the no excisting item, but you can use the salvage arm.
X marks the spot, then use your salvage arm.
get a salvage arm from eddo and go 2 the place with the sacred crest
Finding treasure underwater. It's a huge pain to use but you get the hang of it after a while.
To get the salvage arm you need to get where the sun sign tells you to close the ds together and when you start to go to the boat the mailbox will be 'dancing'. See what you got and it will be Eddo and he will tell you that he has finished the salvage arm.
get a salvage arm and go get the sun key then go to molida island and dig in front of a palm tree
You get the salvage arm at a certain point in the game. You get it from the guy who gave you the cannon
There is no under water land, but there is the sun key in a box on the sea floor. You have to get the Salvage arm and get the box.