If you don’t mind waiting a bit until you uncover significantly cheaper explosives, you can access some dredge locations around the world that have improved ore. has gone One is right there in Gale Cliffs, a 2-way shortcut (as you need 2 explosives to fully clear the shortcut) between the bay where it is and the waterfall area inside the cliffs. Only one explosive is needed to access the dredge site, but it’s still cheaper than getting better ore directly from a traveling merchant.
Other major areas seem to have one of these, but some are a little easier to find. Meru has a spot near the back of the island if you plant around his blackstone island (somewhat between one of the cloth dredge spots and where you initially found the keystones). The space for it in the Tarkii basin has been exhausted by the abandoned resort.
There is another object in the twisted lanes blocked by fallen trees, but where it is in this confusing swamp is a little hard to define. As for the Devil’s Spine, I think there is one too but I was already fully upgraded when I got there so I didn’t really notice it. where is.