Fishfinder and GPS

Fishfinder sat on her perch and hummed happily. “Ah, look at the dots there. Is that a fish?”
GPS turned on his mount. “What’s that? I don’t see anything but that waypoint up ahead.”
“The fish silly, right down there.”
“Down?”
Fishfinder laughed “Of course, Down, what else is there?”
“I don’t understand this ‘Down’ of yours, there’s only Up.”
“Oop? Are there fish there?”
“Up, and no there aren’t any fish. I can’t see what's up there, but I can hear them.”
“How do you know they aren’t fish?”
“Because I don’t know what fish are.”
“Fish are little black dots that make Fisherman push my buttons.”
“Those are waypoints. Fisherman pushes my buttons to make them.”
“Those are different dots. When Boat passes over something, I make the dots.”
GPS looked up “I am only under the sounds.”

Fishfinder pondered this for a moment. “So, fisherman pushes your buttons to make the waypoints, boat passes over something, and I make fish.”
GPS beeped happily “yes, I think you have it! What would Fisherman do without us? Without me, there are no waypoints. Without Boat, there’s nothing to pass over. Without you, there’d be no fish for Fisherman.”
Boat rumbled ominously “Fisherman is pounding my deck in frustration. Stop beeping and get back to work or I’ll put Battery to sleep again.”