The metal detector is actually pretty straightforward to use once you get the hang of it. You'll want to grab a shovel first since you cant dig anything up without one. When youre walking around with the detector, keep an eye on those colored lights, they're super helpful - red means youre pretty far, yellow means getting warmer, and green is like "youre right on top of it." the beeping gets faster too which makes it easier to know when youre close.

Once all the lights turn on and the beeping is going crazy, thats your spot to dig. Takes about three swings with the shovel to get whatever's buried down there. Titanium ore is one of the good finds you can get, along with some cool decorative stuff and those cassette tapes if youre into collecting those. Pretty much any island can have treasure spots, and while some islands might have more spots than others, i usually just sweep the whole place to make sure i dont miss anything.

Just a tip - sometimes the detector can be a bit finnicky with elevation, so if youre getting signals but cant seem to find the right spot try checking different heights on the island.